Methods of bonding hardware to vehicular glass

ABSTRACT

Methods of bonding hardware to glass and other substrates are provided that do not require use of primers, mixing, fixturing, or autoclaving. These methods include the steps of disposing an adhesive layer on a bonding surface of either the hardware or the vehicular glass, the adhesive layer comprising a curable composition that is dimensionally stable at ambient conditions; either before or after disposing the adhesive layer on the bonding surface, irradiating the adhesive layer with ultraviolet radiation to initiate curing of the curable composition; placing the hardware so as to be bonded to the vehicular glass by the adhesive layer; and allowing the adhesive layer to cure.

FIELD OF THE INVENTION

The present invention is directed to methods of adhering structures toglass surfaces, more particularly to methods of adhering structures(e.g., hardware) to vehicular and/or architectural (hereaftervehicular/architectural) glass surfaces, and even more particularly tomethods of adhering hardware (e.g., brackets) to vehicular glasssurfaces such as, e.g., automotive windshields.

BACKGROUND

The glass windshield of a modern automobile serves many functions. Oneis to protect an occupant of the automobile from wind and airbornedebris. Another is to impart strength to the structure of the vehicle.There is also the use of a windshield as a substrate for an assortmentof attachable devices, including mirrors and sensors. New technologieshave resulted in these devices becoming more numerous and sophisticatedover time. These automotive devices can include rain sensors,multifunction cameras, collision avoidance sensors, and lane departurecameras.

To accommodate these devices, automobile manufacturers (i.e., originalequipment manufacturers or “OEMs”) have sought to consolidate devicefunctions to save space and minimize visual obstructions to the driverand other occupants. A common solution is to mount these devices to alarge bracket that is bonded to the upper central portion of thewindshield. The added size of, and weight carried by, these bracketshave introduced new technical challenges to permanently adhering suchhardware to the glass substrate.

Conventionally, the bonding of brackets to glass occurs simultaneouslywith the windshield manufacturing process. In fabricating an automobilewindshield, a thin polymer support layer, such as polyvinyl butyral(PVB), is sandwiched between two layers of tempered glass. These layersare then fused to each other using an autoclave process (i.e., a specialoven that uses heat and pressure) to activate the PVB layer to bond theglass layers together. The same autoclaving process has been used toattach brackets to the glass surface using a heat curable adhesive.These adhesives generally require a certain autoclaving temperature,pressure, and time profile to achieve the required final bond strength.To minimize costs, many windshields are loaded into a single autoclaveand the process executed as a batch.

The larger brackets used in modern automobiles, however, can pose amanufacturing difficulty. Because of their size, they require a muchlarger spacing between windshields within the autoclave. Since fewerwindshields can fit into each autoclave, efficiency is reduced,resulting in a wasted energy, reduced throughput and ultimately,increased costs.

As a solution to the above problem, manufacturers have exploredalternative bonding solutions that allow brackets to be bonded afterautoclaving. These solutions, however, present their own technicalchallenges with respect to initial bond strength and/or required curingtime. For example, conventional liquid adhesives often require a mixingand use of a primer to bond to glass. Many adhesives, based onmoisture-cured or two-part curable polyurethanes, also lack theimmediate green strength needed to prevent the bonded hardware fromslipping along the windshield during curing. As a result, it can benecessary to clamp or tape the hardware to the glass while it cures,which is a cumbersome practice.

Alternative adhesive solutions, such as those described in U.S. Pat. No.8,506,751 (Vandal et al.) require refrigeration of the bonding adhesiveprior to its application to the hardware. Yet, the need for refrigeratedstorage of the adhesive again complicates the process flow and incursadditional costs.

SUMMARY

While these issues are being described in an automotive context, theymay also have relevance in other vehicular markets. Adjacent vehicularmarkets could include, for example, aircraft and marine applications.

Methods of bonding hardware to glass, according to the presentinvention, can overcome the aforementioned difficulties (e.g., notrequiring the use of primers, mixing, fixturing, or autoclaving), andthe process flow resulting from the present invention can alleviatemajor pain points confronted by windshield and other glassmanufacturers. Therefore, the present invention can be seen as beingdirected to a more efficient process for mounting hardware and devicesto the surface of a glass substrate.

In a first aspect of the present invention, a method of bonding hardwareto vehicular glass is provided, where the method comprises: providingthe vehicular glass comprising a first sheet of glass (preferablytempered glass), a polymeric backing, and a second sheet of glass(preferably tempered glass), laminated in that order via an autoclavingprocess; disposing an adhesive layer on a bonding surface of either thehardware or the vehicular glass, the adhesive layer comprising a curablecomposition that is dimensionally stable at ambient conditions; eitherbefore or after disposing the adhesive layer on the bonding surface,irradiating the adhesive layer with ultraviolet radiation to initiatecuring of the curable composition; placing the hardware so as to bebonded to the vehicular glass by the adhesive layer; and allowing theadhesive layer to cure.

In a second aspect of the present invention, a method of bondinghardware to vehicular glass provided, where the method comprises:disposing an adhesive layer on a bonding surface of either the hardwareor the vehicular glass, the adhesive layer comprising a curablecomposition comprised of: a) in the range of from about 25 to about 80parts by weight of one or more epoxy resins, b) in the range of fromabout 5 to about 30 parts by weight of one or more liquid polyetherpolyols, c) in the range of from about 10 to about 50 parts by weight ofone or more hydroxyl-functional film-forming polymers and precursorsthereof, wherein the sum of a) to c) is 100 parts per weight, and d) inthe range of from about 0.1 to about 5 parts by weight of aphotoinitiator, relative to the 100 parts of a) to c); either before orafter disposing the adhesive layer on the bonding surface, irradiatingthe adhesive layer with ultraviolet radiation to initiate curing of thecurable composition; placing the hardware so as to be bonded to thevehicular glass by the adhesive layer; and allowing the adhesive layerto cure.

In a third aspect of the present invention, a method of bonding hardwareto vehicular glass is provided, comprising: disposing an adhesive layeron a bonding surface of either the hardware or the vehicular glass, theadhesive layer comprising a curable composition comprised of: a) in therange of from about 1 to about 50 parts by weight of one or more resinsselected from (meth)acrylate resins; b) in the range of from about 12 toabout 40 parts by weight of one or more hydroxyl-functional film-formingpolymers or precursors thereof; c) in the range of from about 20 toabout 75 parts by weight of one or more epoxy resins; d) in the range offrom about 10 to about 30 parts by weight of one or more polyetherpolyols, wherein the sum of a) to d) is 100 parts by weight; e) in therange of from about 0.1 to about 5 parts by weight of a photoinitiator,relative to the 100 parts of a) to d); either before or after disposingthe adhesive layer on the bonding surface, irradiating the adhesivelayer with ultraviolet radiation to initiate curing of the curablecomposition; contacting the adhesive layer to thevehicular/architectural glass; and allowing the adhesive layer to cure.

In a fourth aspect, a method of bonding hardware to vehicular glasscomprising: disposing an adhesive layer on a bonding surface of eitherthe hardware or the vehicular glass, the adhesive layer comprising acurable composition comprised of: a) in the range of from about 15 toabout 50 parts by weight of a semi-crystalline polyester resin; b) inthe range of from about 20 to about 75 parts by weight of one or moreepoxy resins; c) in the range of from about 5 to about 15 parts byweight of one or more liquid polyether polyols; d) in the range of fromabout 5 to about 20 parts by weight of one or more hydroxyl-functionalfilm-forming polymers and precursors thereof, wherein the sum of a) tod) is 100 parts by weight; and e) in the range of from about 0.1 toabout 5 parts by weight of a photoinitiator, relative to the 100 partsof a) to d); either before or after disposing the adhesive layer on thebonding surface, irradiating the adhesive layer with ultravioletradiation to initiate curing of the curable composition, wherein thephotoinitiator has an ultraviolet absorption curve characterized by ahighest wavelength absorption peak measured at a concentration of about0.03 wt % in acetonitrile solution and wherein the ultraviolet radiationhas a spectral power distribution positively offset from the wavelengthof the highest wavelength absorption peak; placing the hardware so as tobe bonded to the vehicular glass by the adhesive layer; and allowing theadhesive layer to cure.

In a fifth aspect, a method of bonding hardware to vehicular glass isprovided, comprising: disposing an adhesive layer on a bonding surfaceof either the hardware or the vehicular glass, the adhesive layercomprising a photoinitiator having an ultraviolet absorption curvecharacterized by a highest wavelength absorption peak measured at aconcentration of about 0.03 wt % in acetonitrile solution; either beforeor after disposing the adhesive layer on the bonding surface,irradiating the adhesive layer with ultraviolet radiation to initiatecuring of the curable composition, wherein the ultraviolet radiation hasa spectral power distribution positively offset from the wavelength ofthe highest wavelength absorption peak; contacting the adhesive layer tothe vehicular glass; and allowing the adhesive layer to cure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 are schematics showing methods of adhering hardware to glassaccording to various exemplary embodiments.

FIG. 5 shows the spectral power distribution of a source of ultravioletradiation according to an exemplary method of adhering hardware toglass.

FIG. 6 shows an ultraviolet light absorption curve for an exemplarycationic photoinitiator.

Repeated use of reference characters in the specification and drawingsis intended to represent the same or analogous features or elements ofthe disclosure. It should be understood that numerous othermodifications and embodiments can be devised by those skilled in theart, which fall within the scope and spirit of the principles of thedisclosure. Figures may not be drawn to scale.

DEFINITIONS

-   As used herein:

“ambient conditions” means at a temperature of 25° C. and pressure of 1atm (101 kilopascals);

“cure” refers to the process of crosslinking monomers and/or oligomersinto a covalently bonded network;

“cured” means a given material is sufficiently crosslinked to allow forits immediate use in its intended application;

“polyol” means a compound having a hydroxyl functionality of two ormore; and

“semi-crystalline” means having at least some crystalline domains.

DETAILED DESCRIPTION

Described herein, by way of illustration and example, are improvedmethods of bonding hardware to vehicular glass. The hardware, inexemplary embodiments, can include, but not be limited to, buttons andbrackets for mounting various structures such as, for example, side andrear view mirrors, rain sensors, temperature sensors, etc. Vehicularglass, in exemplary embodiments, can include, but are not limited to,windshields and other windows (e.g., skylights, side-facing windows, andrear-facing windows) used in automobiles, trucks, trains, motorcycles,aircraft and water vessels (e.g., boats and ships). The presentinvention may also be useful with architectural glass or otherapplications where something (e.g., hardware) is to be bonded to glass.In exemplary embodiments, the architectural glass can include windows inresidential or commercial buildings such as homes, apartments, officebuildings, restaurants, manufacturing facilities

Preferred methods are described herein and directed to autoclavedautomotive windshields, but these methods are not intended tonecessarily be so limited. Some or all of the provided methods are wellsuited for bonding to other types of vehicular glass, or glasssubstrates more generally.

In useful embodiments, the hardware represents a bracket having anexternal surface adapted for bonding to the curved, interior surface ofa glass windshield. Such brackets may include large format bracketscapable of accommodating multiple accessories such as rain sensors,multifunction cameras, collision avoidance sensors, lane departurecameras, or even one or more peripheral brackets. Additional bracketsmay include those adapted for bonding to tempered glass found in side-and rear-windows of a vehicle.

Alternatively, the hardware could represent a mirror button forattaching a rear view mirror, along with any of its related accessories.

Bonding Methods

FIG. 1 illustrates an exemplary method of bonding hardware to anautomotive windshield according to one exemplary embodiment. The stepsshown merely exemplify the provided methods and need not be exhaustive.Moreover, one or more additional steps may be inserted prior to, after,or between the steps shown in FIG. 1 (and variant FIGS. 2-4) accordingto the knowledge and skill of a professional practicing in this area.

The first step, herein designated by the numeral 100, represents theautoclaving of a layered construction to obtain an automotive windshieldof laminated glass, a type of safety glass that holds together when itis shattered.

Autoclaving is a process by which an article is subjected to highlypressurized hot air or steam. In step 100, a layered construction 102 isreceived in an autoclave 104, which operates to laminate the layers ofthe layered construction 102 to each other. As shown in FIG. 1, thelayered construction includes a pair of tempered glass layers 106, 106disposed on both major surfaces of a polymeric interlayer 108. Temperedglass is a glass that is processed by controlled thermal or chemicaltreatments to increase its strength compared with normal glass.Tempering operates by putting the outward-facing surfaces intocompression and the inward-facing surfaces into tension.

The polymeric interlayer 108 is typically made from a tough, flexiblepolymer such as polyvinyl butyral (“PVB”) or ethylene-vinyl acetate(“EVA”).

The high temperature and pressure provided by the autoclave 104permanently laminates the layers 106, 108, 106 together to provide thelaminated glass.

Referring again to FIG. 1, step 110 shows the process of placing abracket 112 having a pre-applied adhesive layer 114 to be bonded ontothe now-laminated layered construction 102. As shown, this is a two-stepprocess.

First, the adhesive layer 114 is irradiated with actinic radiation, suchas ultraviolet (“UV”) radiation 118, to initiate a curing reaction inthe adhesive layer 114. As shown, the UV radiation 118 is directedthrough the adhesive layer 114 and onto the underlying bonding surface116 of the bracket 112. As an alternative, the UV radiation 118 can betransmitted through the bracket itself if the bracket is made from amaterial translucent to the curing radiation.

Second, as shown in the second part of step 110, the bracket 112 andadhesive layer 114 are collectively mounted onto the autoclaved layeredconstruction 102 to form a bonded assembly 119. In the bonded assembly119, the adhesive layer 114 directly contacts one of the glass layers106.

The adhesive layer 114 is preferably a die-cut adhesive layer.Optionally, the die-cut adhesive layer can be tailored to match thefootprint of the bonding surfaces of the bracket 112 such that theadhesive layer 114 does not extend beyond the peripheral edges of thebracket 112. If desired, two or more die-cut adhesive layers may bedisposed side-to-side on the bonding surfaces.

The adhesive layer 114 contains a mixture of monomers/oligomers and asuitable photoinitiator that can be activated by UV radiation topolymerize the monomer components. Various UV light sources can be usedfor this purpose.

One type of UV source is a relatively low light intensity source such asa black light which provides generally 10 mW/cm² or less (as measured inaccordance with procedures approved by the United States NationalInstitute of Standards and Technology as, for example, with a UVIMAP™ UM365 L-S radiometer manufactured by Electronic Instrumentation &Technology, Inc., in Sterling, Va.) over a wavelength range of 280 nm to400 nm.

A second, higher light intensity UV source is a broad spectrum mercurylamp, which can provide intensities generally greater than 10 mW/cm²,and preferably between 15 and 3000 mW/cm². For example, an intensity of600 mW/cm² and an exposure time of about 1 second may be usedsuccessfully. Intensities can range from 0.1 mW/cm² to 6000 mW/cm² andpreferably from 0.5 mW/cm² to 3000 mW/cm².

A third type of light source is a light emitting diode (“LED”) UVsource. LED-based UV sources are advantageous because they are capableof generating UV light over a much narrower wavelength range comparedwith black lights and mercury lamps.

In step 120, the composition of the adhesive layer 114 in the bondedassembly 119 is allowed to cure (or crosslink) over time.Advantageously, the adhesive layer 114 has sufficient tack anddimensional stability to eliminate the necessity of clamping or usingany other type of mechanism to secure the bracket 112 to the glass layer106 as the curing reaction proceeds.

The irradiation of the adhesive layer 114 in step 110 is preferablysufficient to achieve a functional cure of the adhesive layer 114 underambient conditions. As an option, however, the time required to reach afunctional cure can be accelerated with heat, typically by baking thebonded assembly 119 in an oven for a pre-determined period of time.

The post-cure bake for an onium salt type photoinitiator can last for atleast 2 minutes, at least 3 minutes, or at least 5 minutes. On the upperend, the post-cure bake may be sustained up to 35 minutes, up to 25minutes, or up to 15 minutes. The temperature of the post-cure bake canbe, for example, at least 35° C., at least 70° C., or at least 90° C.The temperature can be at most 180° C., at most 150° C., or at most 120°C.

Each of FIGS. 2-4 shows a variation on the aforementioned method ofbonding. Differences are pointed out below, but those aspects of eachmethod not expressly defined below can be substantially similar to thosedescribed with respect to the method of bonding shown in FIG. 1.

FIG. 2 illustrates an alternative to steps 110, 120 in the bonding ofthe same bracket 112 to the same autoclaved laminated glass. First, instep 200, the adhesive layer 114 is placed in contact with the glasslayer 106 at the outset and then irradiated with the UV radiation 118 toinitiate curing of the adhesive. Then, in step 210, the bracket 112 isplaced into contact with the adhesive layer 114 to provide the bondedassembly 119 shown in step 220. Finally, in step 230, the adhesive layer114 of the bonded assembly 119 is allowed to cure over time.

FIG. 3 illustrates another alternative to steps 110, 120 of FIG. 1. Instep 300 of this variant, the adhesive layer 114 is irradiated using theUV light 118 as a stand-alone layer, as shown. Optionally but not shown,the adhesive layer 114 could be provided on a release liner that isremoved before or after irradiation. In step 310, the adhesive layer 114is then placed in contact with the bracket 112 and layered construction102, adhering them to each other to provide the bonded assembly 119shown in step 330. Finally, the adhesive layer 114 of the bondedassembly 119 is allowed to cure over time as shown in step 330.

FIG. 4 independently shows another method of bonding to glass. In step400, the bracket 112 is adhered onto a glass layer 406 using theadhesive layer 114 to form the bonded assembly 119. The bonded assembly119 is then irradiated with the UV light 118 to initiate curing of theadhesive layer 114. In a subsequent step 410, the adhesive layer 114 isallowed to cure over time.

Adhesive Compostions

The adhesive layer can be made from any of a number of usefulUV-activated adhesives. Preferred adhesives include structural bondingadhesives having high strength and adhesion properties.

UV-activated adhesives do not require heat for curing, although asmentioned above, heat can be used to accelerate the curing process afteractivation. The structural bonding adhesive is useful for bondinghardware to glass, but can also be effective in bonding together one ormore substrates generally.

In preferred embodiments, the adhesive is prepared using a hot meltprocess, thereby avoiding the need for volatile solvents. Use of thesesolvents is often undesirable because of costs associated withprocurement, handling and disposal of these components.

Useful components in the adhesive layer used for bonding hardware toglass are enumerated and described under the subheadings below.

Tetrahydrofurfuryl(meth)acrylate Copolymers

In certain embodiments, the adhesive comprises a tetrahydrofurfuryl(THF) (meth)acrylate copolymer component. Unless otherwise specified,the THF acrylates and methacrylates will be abbreviated as THFA. Moreparticularly, it comprises a copolymer of tetrahydrofurfuryl(meth)acrylate, a C₁-C₈ (meth)acrylate ester and an optionalcationically reactive functional (meth)acrylate.

The copolymer further comprises a C₁-C₈ alkyl (meth)acrylate estermonomer. Useful monomers include the acrylates and methacrylate ofmethyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl and octylalcohols, including all isomers, and mixtures thereof. It is preferredthat the alcohol is selected from C₃-C₆ alkanols, and in certainembodiments, the carbon number molar average of the alkanols isC₃-C_(6.) It has been found that within this range the copolymer hassufficient miscibility with the epoxy resin component and it allows forformulation of a UVi SBT with a useful overall balance of adhesiveproperties, including overlap shear adhesion.

The carbon number molar average may be calculated by summing the numberof moles of each alkanol (C₁-C₈ alkanols) multiplied by the carbonnumber of each alkanol, and dividing the result by the total number ofmoles of alkanols: i.e.,

Σ_(α-ω)[(Moles of alkanol)×(# carbon atoms for alkanol)]/# moles ofalkanols α to ω.

In addition, the copolymer may contain a cationically reactive monomer,i.e., a (meth)acrylate monomer having a cationically reactive functionalgroup. Examples of such monomers include, for example, glycidylacrylate, glycidyl methacrylate, hydroxyethyl acrylate, hydroxyethylmethacrylate, hydroxypropyl methylacrylate, hydroxybutyl acrylate andalkoxysilylalkyl (meth)acrylates, such as trimethoxysilylpropylacrylate.

For stability of the polymerizable composition, the copolymer containsessentially no acid functional monomers, whose presence could initiatepolymerization of the epoxy resin prior to UV curing. For the samereason, it is preferred that the copolymer not contain anyamine-functional monomers. Furthermore, it is preferred that thecopolymer not contain any acrylic monomers having moieties sufficientlybasic so as to inhibit cationic cure of the adhesive composition.

The THFA copolymer generally comprises polymerized monomer units of: (A)40-60 wt %, and preferably 50-60 wt %, of tetrahydrofurfuryl(meth)acrylate; (B) 40-60 wt %, and preferably 40-50 wt %, of C₁-C₈(preferably C₃-C₆) alkyl (meth)acrylate ester monomers; and (C) 0-10 wt%, and preferably 1-5 wt % of cationically reactive functional monomers,wherein the sum of A)-C) is 100 wt %.

The adhesive compositions can comprise one or more THFA copolymers invarious amounts, depending on the desired properties of the adhesive.Desirably, the adhesive composition comprises one or more THFAcopolymers in an amount of from 15-50 parts, and preferably 25-35 parts,by weight based on 100 parts total weight of monomers/copolymers in theadhesive composition.

Thermoplastic Polyesters

The provided adhesives may include one or more thermoplastic polyesters.Suitable polyester components include semi-crystalline polyesters aswell as amorphous and branched polyesters.

Thermoplastic polyesters may include polycaprolactones and polyestershaving hydroxyl and carboxyl termination, and may be amorphous orsemi-crystalline at room temperature. More preferred are hydroxylterminated polyesters that are semi-crystalline at room temperature. Amaterial that is “amorphous” has a glass transition temperature but doesnot display a measurable crystalline melting point as determined on adifferential scanning calorimeter (“DSC”). Preferably, the glasstransition temperature is less than about 100° C. A material that is“semi-crystalline” displays a crystalline melting point as determined byDSC, preferably with a maximum melting point of about 120° C.

Crystallinity in a polymer can also be reflected by the clouding oropaqueness of a sheet that had been heated to an amorphous state as itcools. When the polyester polymer is heated to a molten state andknife-coated onto a liner to form a sheet, it is amorphous and the sheetis observed to be clear and fairly transparent to light. As the polymerin the sheet material cools, crystalline domains form and thecrystallization is characterized by the clouding of the sheet to atranslucent or opaque state. The degree of crystallinity may be variedin the polymers by mixing in any compatible combination of amorphouspolymers and semi-crystalline polymers having varying degrees ofcrystallinity. It is generally preferred that material heated to anamorphous state be allowed sufficient time to return to itssemi-crystalline state before use or application. The clouding of thesheet provides a convenient non-destructive method of determining thatcrystallization has occurred to some degree in the polymer.

The polymers may include nucleating agents to increase the rate ofcrystallization at a given temperature. Useful nucleating agents includemicrocrystalline waxes. A suitable wax could include an alcoholcomprising a carbon chain having a length of greater than 14 carbonatoms (CAS #71770-71-5) or an ethylene homopolymer (CAS #9002-88-4) soldby Baker Hughes, Houston, Tex., as UNILIN™ 700.

Preferred polyesters are solid at room temperature. Preferred polyestermaterials have a number average molecular weight of about 7,500 g/mol to200,000 g/mol, more preferably from about 10,000 g/mol to 50,000 g/mol,and most preferably, from about 15,000 g/mol to 30,000 g/mol.

Polyester components useful in the invention comprise the reactionproduct of dicarboxylic acids (or their diester equivalents) and diols.The diacids (or diester equivalents) can be saturated aliphatic acidscontaining from 4 to 12 carbon atoms (including branched, unbranched, orcyclic materials having 5 to 6 carbon atoms in a ring) and/or aromaticacids containing from 8 to 15 carbon atoms. Examples of suitablealiphatic acids are succinic, glutaric, adipic, pimelic, suberic,azelaic, sebacic, 1,12-dodecanedioic, 1,4-cyclohexanedicarboxylic,1,3-cyclopentanedicarboxylic, 2-methylsuccinic, 2-methylpentanedioic,3-methylhexanedioic acids, and the like. Suitable aromatic acids includeterephthalic acid, isophthalic acid, phthalic acid, 4,4′-benzophenonedicarboxylic acid, 4,4′-diphenylmethanedicarboxylic acid,4,4′-diphenylthioether dicarboxylic acid, and 4,4′-diphenylaminedicarboxylic acid. Preferably, the structure between the two carboxylgroups in the diacids contain only carbon and hydrogen, and morepreferably, the structure is a phenylene group. Blends of the foregoingdiacids may be used.

The diols include branched, unbranched, and cyclic aliphatic diolshaving from 2 to 12 carbon atoms. Examples of suitable diols includeethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol,1,4-butanediol, 1,3-butanediol, 1,5-pentanediol,2-methyl-2,4-pentanediol, 1,6-hexanediol,cyclobutane-1,3-di(2′-ethanol), cyclohexane-1,4-dimethanol,1,10-decanediol, 1,12-dodecanediol, and neopentyl glycol. Long chaindiols including poly(oxyalkylene)glycols in which the alkylene groupcontains from 2 to 9 carbon atoms, preferably 2 to 4 carbon atoms, mayalso be used. Blends of the foregoing diols may be used.

Useful, commercially available hydroxyl terminated polyester materialsinclude various saturated linear, semi-crystalline copolyestersavailable from Evonik Industries, Essen, North Rhine-Westphalia,Germany, such as DYNAPOL™ S1401, DYNAPOL™ S1402, DYNAPOL™ S1358,DYNAPOL™ S1359, DYNAPOL™ S1227, and DYNAPOL™ S1229. Useful saturated,linear amorphous copolyesters available from Evonik Industries includeDYNAPOL™ 1313 and DYNAPOL™ S1430.

The adhesive may include one or more thermoplastic polyesters in anamount that varies depending on the desired properties of the adhesivelayer. Desirably, the adhesive includes one or more thermoplasticpolyesters in an amount of up to 50 percent by weight, based on thetotal weight of monomers/copolymers in the adhesive composition. Wherepresent, the one or more thermoplastic polyesters are preferably presentin an amount of at least 5 percent, at least 10 percent, at least 12percent, at least 15 percent, or at least 20 percent by weight based onthe total weight of monomers/copolymers in the adhesive composition.Where present, the one or more thermoplastic polyesters are preferablypresent in an amount of at most 20 percent, at most 25 percent, at most30 percent, at most 40 percent, or at most 50 percent by weight based onthe total weight of monomers/copolymers in the adhesive composition.

Epoxy Resins

In preferred embodiments, the adhesive comprises one or more epoxyresins, which are polymers characterized by epoxide functional groups.Epoxy resins or epoxides that are useful in the composition of thepresent disclosure may be any organic compound having at least oneoxirane ring that is polymerizable by ring opening, i.e., an averageepoxy functionality greater than one, and preferably at least two. Theepoxides can be monomeric or polymeric, and aliphatic, cycloaliphatic,heterocyclic, aromatic, hydrogenated, or mixtures thereof. Preferredepoxides contain more than 1.5 epoxy group per molecule and preferablyat least 2 epoxy groups per molecule. The useful materials typicallyhave a weight average molecular weight of 150 g/mol to 10,000 g/mol, andmore typically 180 g/mol to 1,000 g/mol. The molecular weight of theepoxy resin is usually selected to provide the desired properties of thecured adhesive. Suitable epoxy resins include linear polymeric epoxideshaving terminal epoxy groups (e.g., a diglycidyl ether of apolyoxyalkylene glycol), polymeric epoxides having skeletal epoxy groups(e.g., polybutadiene poly epoxy), and polymeric epoxides having pendantepoxy groups (e.g., a glycidyl methacrylate polymer or copolymer), andmixtures thereof. The epoxide-containing materials include compoundshaving the general formula:

where R¹ is an alkyl, alkyl ether, or aryl group and n is in the rangeof from 1 to 6.

Epoxy resins include aromatic glycidyl ethers, e.g., such as thoseprepared by reacting a polyhydric phenol with an excess ofepichlorohydrin, cycloaliphatic glycidyl ethers, hydrogenated glycidylethers, and mixtures thereof. Such polyhydric phenols may includeresorcinol, catechol, hydroquinone, and the polynuclear phenols such asp,p′-dihydroxydibenzyl, p,p′-dihydroxydiphenyl, p,p′-dihydroxyphenylsulfone, p,p′-dihydroxybenzophenone,2,2′-dihydroxy-1,1-dinaphthylmethane, and the 2,2′, 2,3′, 2,4′, 3,3′,3,4′, and 4,4′ isomers of dihydroxydiphenylmethane,dihydroxydiphenyldimethylmethane, dihydroxydiphenylethylmethylmethane,dihydroxydiphenylmethylpropylmethane,dihydroxydiphenylethylphenylmethane,dihydroxydiphenylpropylphenylmethane,dihydroxydiphenylbutylphenylmethane, dihydroxydiphenyltolylethane,dihydroxydiphenyltolylmethylmethane,dihydroxydiphenyldicyclohexylmethane, and dihydroxydiphenylcyclohexane.

Also useful are polyhydric phenolic formaldehyde condensation productsas well as polyglycidyl ethers that contain as reactive groups onlyepoxy groups or hydroxy groups. Useful curable epoxy resins are alsodescribed in various publications including, for example, “Handbook ofEpoxy Resins” by Lee and Nevill, McGraw-Hill Book Co., New York (1967),and Encyclopedia of Polymer Science and Technology, 6, p.322 (1986).

The choice of the epoxy resin used depends upon its intended end use.For example, epoxides with flexible backbones may be desired where agreater amount of ductility is needed in the bond line. Materials suchas diglycidyl ethers of bisphenol A and diglycidyl ethers of bisphenol Fcan provide desirable structural adhesive properties that thesematerials attain upon curing, while hydrogenated versions of theseepoxies may be useful for compatibility with substrates having oilysurfaces.

Examples of commercially available epoxides useful in the presentdisclosure include diglycidyl ethers of bisphenol A (e.g, thoseavailable under the trade names EPON™ 828, EPON™ 1001, EPON™ 1004, EPON™2004, EPON™ 1510, and EPON™ 1310 from Momentive Specialty Chemicals,Inc., Waterford, N.Y. and those under the trade designations D.E.R.™331, D.E.R.™ 332, D.E.R.™ 334, and D.E.N.™ 439 available from DowChemical Co., Midland, Mich.); diglycidyl ethers of bisphenol F (thatare available, e.g., under the trade designation ARALDITE™ GY 281available from Huntsman Corporation); silicone resins containingdiglycidyl epoxy functionality; flame retardant epoxy resins (e.g., thatare available under the trade designation D.E.R.™ 560, a brominatedbisphenol type epoxy resin available from Dow Chemical Co.); and1,4-butanediol diglycidyl ethers.

Epoxy containing compounds having at least one glycidyl ether terminalportion, and preferably, a saturated or unsaturated cyclic backbone mayoptionally be added to the composition as reactive diluents. Reactivediluents may be added for various purposes such as to aid in processing,e.g., to control the viscosity in the composition as well as duringcuring, make the cured composition more flexible, and/or compatibilizematerials in the composition.

Examples of such diluents include: diglycidyl ether ofcyclohexanedimethanol, diglycidyl ether of resorcinol, p-tert-butylphenyl glycidyl ether, cresyl glycidyl ether, diglycidyl ether ofneopentyl glycol, triglycidyl ether of trimethylolethane, triglycidylether of trimethylolpropane, triglycidyl p-amino phenol,N,N′-diglycidylaniline, N,N,N′N′-tetraglycidyl meta-xylylene diamine,and vegetable oil polyglycidyl ether. Reactive diluents are commerciallyavailable as HELOXY™ 107 and CARDURA™ N10 from Momentive SpecialtyChemicals, Inc. The composition may contain a toughening agent to aid inproviding the desired overlap shear, peel resistance, and impactstrength.

The adhesive composition desirably contains one or more epoxy resinshaving an epoxy equivalent weight of from 100 g/mol to 1500 g/mol. Moredesirably, the adhesive contains one or more epoxy resins having anepoxy equivalent weight of from 300 g/mol to 1200 g/mol. Even moredesirably, the adhesive contains two or more epoxy resins, wherein atleast one epoxy resin has an epoxy equivalent weight of from 300 g/molto 500 g/mol, and at least one epoxy resin has an epoxy equivalentweight of from 1000 g/mol to 1200 g/mol.

The adhesive composition may comprise one or more epoxy resins in anamount, which varies depending on the desired properties of thestructural adhesive layer. Desirably, the adhesive composition comprisesone or more epoxy resins in an amount of at least 20, at least 25, atleast 35, at least 40, at least 50 parts, or at least 55 parts byweight, based on the 100 parts total weight of the adhesive composition.In desirable embodiments, the one or more epoxy resins are present in anamount of at most 45, at most 50 parts, at most 75 parts, or at most 80parts by weight, based on the 100 parts total weight of themonomers/copolymers in the adhesive composition.

Vinyl Ethers

Vinyl ethers represent a different class of monomers that, like epoxyresins, are cationic polymerizable. These monomers can be used as analternative to, or in combination with, the epoxy resins disclosedherein.

The vinyl ether monomer has a high electron density of double bonds andproduces a stable carbocation, enabling this monomer to have highreactivity in cationic polymerizations. To avoid inhibiting the cationicpolymerization, the vinyl ether monomer may be limited to those notcontaining nitrogen. Examples thereof include methyl vinyl ether, ethylvinyl ether, tert-butyl vinyl ether, isobutyl vinyl ether, triethyleneglycol divinyl ether, and 1,4-cyclohexane dimethanol divinyl ether.Preferred examples of the vinyl ether monomer include triethylene glycoldivinyl ether and cyclohexane dimethanol divinyl ether (both sold underthe trade designation RAPI-CURE by Ashland, Inc., Covington, Ky.).

Liquid Polyether Polyols

The adhesive composition can further include one or more liquid (underambient conditions) hydroxy-functional polyether. Preferably, the one ormore hydroxy-functional polyethers include a polyether polyol. Thepolyether polyol can be present in an amount of at least 5 parts, atleast 10 parts, or at most 15 parts relative to 100 parts total weightof monomers/copolymers in the adhesive composition. In some embodiments,the polyether polyol is present in an amount of at most 15 parts, atmost 20 parts, or at most 30 parts relative to 100 parts total weight ofmonomers/copolymers in the adhesive composition.

Examples of hydroxy-functional polyethers include, but are not limitedto, polyoxyethylene and polyoxypropylene glycols; polyoxyethylene andpolyoxypropylene triols and polytetramethylene oxide glycols.

In the provided methods of bonding, the polyoxyalkylene polyols areparticularly suitable for retarding the curing reaction so that the opentime of the adhesive composition can be increased. As used herein, the“open time” refers to the period of time after an adhesive compositionhas been irradiated, during which time the adhesive composition remainssufficiently uncured for a second substrate to be bonded thereto.

The open time of the adhesive composition is preferably at least 2minutes after exposure to an energy dose of about 1.6 J/cm² of actinicradiation. If, however, one or both adherends to be bonded together aretranslucent to UV radiation to which the structural adhesive layer is tobe exposed, then open time is of lesser relevance. In these cases, UVirradiation can be effected through the translucent substrate afteradherends have been mutually attached. When both substrates of theassembly are opaque, the adhesive can be exposed to actinic radiationprior to attaching the second substrate thereto. In this case, an opentime of at least 2 minutes is desirable to allow for suitableworkability of the structural adhesive layer.

Suitable hydroxy-functional poly(alkylenoxy) compounds include, but arenot limited to, the POLYMEG™ series of polytetramethylene oxide glycols(from Lyondellbasell, Inc., Jackson, Tenn.), the TERATHANE™ series ofpolytetramethylene oxide glycols (from Invista, Newark, Del.); thePOLYTHF™ series of polytetramethylene oxide glycol (from BASF SE,Ludwigshafen, Germany); the ARCOL™ series of polyoxypropylene polyols(from Bayer MaterialScience LLC, Pittsburgh, Pa.) and the VORANOL™series of polyether polyols (from Dow Chemical Company, Midland, Mich.).

Hydroxyl-Functional Film-Forming Polymers

The adhesive layer further contains at least one hydroxyl-functionalfilm-forming polymer having at least one and desirably at least twohydroxyl groups. As used herein, the term “hydroxyl-functionalfilm-forming polymer” does not include the polyether polyols describedabove, which also contain hydroxyl groups. Desirably, the film-formingpolymer are substantially free of other “active hydrogen” containinggroups such as amino and mercapto moieties. Further, the film-formingpolymer or polymers are also desirably substantially free of groups,which may be thermally and/or photolytically unstable so that thecompounds will not decompose when exposed to actinic radiation and/orheat during curing.

The hydroxyl-containing film-forming polymer contains two or moreprimary or secondary aliphatic hydroxyl groups (i.e., the hydroxyl groupis bonded directly to a non-aromatic carbon atom). In some embodiments,the hydroxyl-functional film-forming polymer has a hydroxyl number of atleast 0.01. It is believed the hydroxyl groups participate in thecationic polymerization with the epoxy resin.

The hydroxyl-functional film-forming polymer may be selected fromphenoxy resins, ethylene-vinyl acetate (“EVA”) copolymers (which aresolid under ambient conditions), polycaprolactone polyols, polyesterpolyols, and polyvinyl acetal resins that are solid under ambientconditions. The hydroxyl group may be terminally situated, or may bependent from a polymer or copolymer. Advantageously, the addition of afilm-forming polymer to the adhesive composition can improve the dynamicoverlap shear strength and/or decrease the cold flow of the adhesivelayer.

One useful class of hydroxyl-containing film-forming polymers ishydroxy-containing phenoxy resins. Desirable phenoxy resins includethose derived from the polymerization of a diglycidyl bisphenolcompound. Typically, the phenoxy resin has a number average molecularweight of less than 60,000 g/mol, desirably in the range of 20,000 g/molto 30,000 g/mol. Commercially available phenoxy resins include, but arenot limited to, PAPHEN™ PKHP-200, available from Inchem Corp., RockHill, S.C. and the SYN FAC™ series of polyoxyalkylated bisphenol A fromMilliken Chemical, Spartanburg, S.C.) such as SYN FAC™ 8009, 8024, 8027,8026, and 8031.

Another useful class of hydroxyl-containing film-forming polymers isthat of EVA copolymer resins. It is believed that these resins containsmall amounts of free hydroxyl groups, and that EVA copolymers arefurther deacetylated during cationic polymerization. Hydroxyl-containingEVA resins can be obtained, for example, by partially hydrolyzing aprecursor EVA copolymer.

Suitable ethylene-vinyl acetate copolymer resins include, but are notlimited to, thermoplastic EVA copolymer resins containing at least 28percent by weight vinyl acetate. In one embodiment, the EVA copolymercomprises a thermoplastic copolymer containing at least 28 percent byweight vinyl acetate, desirably at least 40 percent by weight vinylacetate, more desirably at least 50 percent by weight vinyl acetate, andeven more desirably at least 60 percent by weight vinyl acetate byweight of the copolymer. In a further embodiment, the EVA copolymercontains an amount of vinyl acetate in the range of from 28 to 99 weightpercent of vinyl acetate, desirably from 40 to 90 weight percent ofvinyl acetate, more desirably from 50 to 90 weight percent of vinylacetate, and even more desirably from 60 to 80 weight percent vinylacetate in the copolymer.

Examples of commercially available EVA copolymers include, but are notlimited to, the ELVAX™ series, including ELVAX™ 150, 210, 250, 260, and265 from E. I. Du Pont de Nemours and Co., Wilmington, Del., ATEVA™series from Celanese, Inc., Irving, Tex.); LEVAPREN™ 400 from BayerCorp., Pittsburgh, Pa. including LEVAPREN™ 450, 452, and 456 (45 weightpercent vinyl acetate); LEVAPREN™ 500 HV (50 weight percent vinylacetate); LEVAPREN™ 600 HV (60 weight percent vinyl acetate); LEVAPREN™700 HV (70 weight percent vinyl acetate); and LEVAPREN™ KA 8479 (80weight percent vinyl acetate), each from Lanxess Corp., Cologne,Germany.

Additional useful film-forming polymers include the TONE™ series ofpolycaprolactone polyols series available from Dow Chemical, the CAPA™series of polycaprolactone polyols from Perstorp Inc., Perstorp, Sweden,and the DESMOPHEN™ series of saturated polyester polyols from BayerCorporation, Pittsburgh, Pa., such as DESMOPHEN™ 631A 75.

The adhesive layer comprises one or more hydroxyl-containingfilm-forming polymers resins in an amount, which varies depending on thedesired properties of the structural adhesive layer. The adhesivecomposition can include one or more hydroxyl-containing film-formingpolymer resins in an amount of at least 10 parts, at least 15 parts, atleast 20 parts, or at least 25 parts by weight, based on 100 parts totalweight of monomers/copolymers in the adhesive composition. In someembodiments, the one or more hydroxyl-containing film-forming polymerresins can be present in an amount of at most 20 parts, at most 25parts, or at most 50 parts, based on 100 parts total weight ofmonomers/copolymers in the adhesive composition.

Photoinitiators

Useful photoinitiators include photoinitiators used to i) polymerizeprecursor polymers (for example, in some embodiments, tetrahydrofurfuryl(meth)acrylate copolymer) and ii) those used to ultimately polymerizethe adhesive layer bonding the hardware to vehicular glass or any othersubstrate.

Photoinitiators for the former include benzoin ethers such as benzoinmethyl ether and benzoin isopropyl ether; substituted acetophenones suchas 2,2 dimethoxy-1,2-diphenylethanone, available as IRGACURE™ 651 (BASFSE) or ESACURE™ KB-1 (Sartomer Co., West Chester, Pa.),dimethoxyhydroxyacetophenone; substituted α-ketols such as2-methyl-2-hydroxy propiophenone; aromatic sulfonyl chlorides such as2-naphthalene-sulfonyl chloride; and photoactive oximes such as1-phenyl-1,2-propanedione-2-(O-ethoxy-carbonyl)oxime. Particularlypreferred among these are the substituted acetophenones.

Preferred photoinitiators are photoactive compounds that undergo aNorrish I cleavage to generate free radicals that can initiate byaddition to the acrylic double bonds. Such photoinitiators preferablyare present in an amount of from 0.1 to 1.0 pbw per 100 parts of theprecursor polymer composition.

Photoinitiators particularly useful for the latter include ionicphotoacid generators, which are compounds that can generate acids uponexposure to actinic radiation. These are extensively used to initiatecationic polymerizations, in which case they are referred to as cationicphotoinitiators.

Useful ionic photoacid generators include bis(4-t-butylphenyl) iodoniumhexafluoroantimonate (FP5034™ from Hampford Research Inc., Stratford,Conn.), a mixture of triarylsulfonium salts (diphenyl(4-phenylthio)phenylsufonium hexafluoroantimonate,bis(4-(diphenylsulfonio)phenyl)sulfide hexafluoroantimonate) availableas Syna PI-6976™ from Synasia Metuchen, N.J., (4-methoxyphenyl)phenyliodonium triflate, bis(4-fert-butylphenyl) iodonium camphorsulfonate,bis(4-tert-butylphenyl) iodonium hexafluoroantimonate,bis(4-tert-butylphenyl) iodonium hexafluorophosphate,bis(4-tert-butylphenyl) iodonium tetraphenylborate,bis(4-tert-butylphenyl) iodonium tosylate, bis(4-tert-butylphenyl)iodonium triflate, ([4-(octyloxy)phenyl]phenyliodoniumhexafluorophosphate), ([4-(octyloxy)phenyl]phenyliodoniumhexafluoroantimonate), (4-isopropylphenyl)(4-methylphenyl)iodoniumtetrakis(pentafluorophenyl) borate (available as Rhodorsil 2074™ fromBluestar Silicones, East Brunswick, N.J.), bis(4-methylphenyl) iodoniumhexafluorophosphate (available as Omnicat 440™ from IGM Resins Bartlett,Ill.), 4-(2-hydroxy-1-tetradecycloxy)phenyl]phenyl iodoniumhexafluoroantimonate, triphenyl sulfonium hexafluoroantimonate(available as CT-548™ from Chitec Technology Corp. Taipei, Taiwan),diphenyl(4-phenylthio)phenylsufonium hexafluorophosphate,bis(4-(diphenylsulfonio)phenyl)sulfide bis(hexafluorophosphate),diphenyl(4-phenylthio)phenylsufonium hexafluoroantimonate,bis(4-(diphenylsulfonio)phenyl)sulfide hexafluoroantimonate, and blendsof these triarylsulfonium salts available from Synasia, Metuchen, N.J.as SYNA™ PI-6992 and SYNA™ PI-6976 for the PF₆ and SbF₆ salts,respectively. Similar blends of ionic photoacid generators are availablefrom Aceto Pharma Corporation, Port Washington, N.Y. as UVI-6992 andUVI-6976.

The photoinitiator is used in amounts sufficient to effect the desireddegree of crosslinking of the copolymer. The desired degree ofcrosslinking may vary, depending on the desired adhesive properties andthe film thickness. The amount of the photoinitiator necessary to effectthe desired degree of crosslinking will depend on the quantum yield ofthe photoinitiator (the number of molecules of acid released per photonabsorbed), the permeability of the polymer matrix, the wavelength andduration of irradiation and the temperature. Generally thephotoinitiator is used in amounts of at least 0.001 parts, at least0.005 parts, at least 0.01 parts, at least 0.05 parts, at least 0.1parts, or at least 0.5 parts by weight relative to 100 parts by weightof total monomer/copolymer in the adhesive composition. Thephotoinitiator is generally used in amounts of at most 5 parts, at most3 parts, at most 1 part, at most 0.5 parts, at most 0.3 parts, or atmost 0.1 parts by weight relative to 100 parts by weight of totalmonomer/copolymer in the adhesive composition.

Optional Additives

The adhesive composition may further contain any of a number of optionaladditives. Such additives may be homogeneous or heterogeneous with oneor more components in the adhesive composition. Heterogenous additivesmay be discrete (e.g., particulate) or continuous in nature.

Aforementioned additives can include, for example, fillers, stabilizers,plasticizers, tackifiers, flow control agents, cure rate retarders,adhesion promoters (for example, silanes and titanates), adjuvants,impact modifiers, expandable microspheres, thermally conductiveparticles, electrically conductive particles, and the like, such assilica, glass, clay, talc, pigments, colorants, glass beads or bubbles,and antioxidants, so as to reduce the weight and/or cost of thestructural adhesive layer composition, adjust viscosity, and/or provideadditional reinforcement or modify the thermal conductivity of adhesivecompositions and articles used in the provided methods so that a morerapid or uniform cure may be achieved.

In some embodiments, the adhesive contains one or more fiberreinforcement materials. Advantageously, use of a fiber reinforcementmaterial can provide a structural adhesive layer that has improved coldflow properties, limited stretchability, and enhanced strength.Preferably, the one or more fiber reinforcement materials has a certaindegree of porosity that enables the photoinitiator, which is generallydispersed throughout the adhesive, to be activated by UV light andproperly cured without the need for heat. The one or more fiberreinforcements may comprise one or more fiber-containing webs including,but not limited to, woven fabrics, nonwoven fabrics, knitted fabrics,and a unidirectional array of fibers. The one or more fiberreinforcements could comprise a nonwoven fabric, such as a scrim.

Materials for making the one or more fiber reinforcements may includeany fiber-forming material capable of being formed into one of theabove-described webs. Suitable fiber-forming materials include, but arenot limited to, polymeric materials such as polyesters, polyolefins, andaramids; organic materials such as wood pulp and cotton; inorganicmaterials such as glass, carbon, and ceramic; coated fibers having acore component (i.e., any of the above fibers) and a coating thereon;and combinations thereof.

Further options and advantages of the fiber reinforcement materials aredescribed in U.S. Patent Publication No. 2002/0182955 (Weglewski etal.).

Curing Conditions

As discussed earlier, the monomer mixture and the photoinitiator may beirradiated using various activating UV light sources to polymerize themonomer component(s).

Light sources based on light emitting diodes can enable a number ofsurprising advantages with respect to the provided methods of bonding.These light sources can be monochromatic, which for the purposes of thisdisclosure implies that the spectral power distribution is characterizedby a very narrow wavelength distribution (i.e., confined within a 50 nmrange or less). Advantageously, monochromatic ultraviolet light canreduce thermal damage or harmful deep UV effects to coatings andsubstrates being irradiated. In larger scale applications, the lowerpower consumption of UV-LED sources can also allow for energy savingsand reduced environmental impact.

FIG. 5 shows the spectral power distribution of an exemplary UV-LEDlight source having a peak (designated with the numeral 500)characterized by a wavelength (at peak intensity) of approximately 365nm. As FIG. 5 illustrates, the UV-LED light source emits light over anarrow range of wavelengths around 365 nm. More generally, the spectralpower distribution can show a peak intensity at a wavelength of at least315 nm, at least 330 nm, or at least 350 nm. In some embodiments, thespectral power distribution shows a peak intensity at a wavelength of atmost 400 nm, at most 390 nm, or at most 380 nm.

As an option, the spectral power distribution can substantially excludelight output at wavelengths below a threshold value. The thresholdwavelength value could be, for example, 280 nm, 290 nm, or 300 nm. Aswill be described in more detail below, a low wavelength cutoff can beadvantageous in providing more uniform kinetics in adhesivepolymerization along the thickness dimension of the adhesive layer.

It was discovered that matching the spectral power distribution of thephotoinitiator with the absorption spectrum of UV light source tooclosely can result in inferior curing of thick adhesive layers. Withoutintending to be bound by theory, it is believed that aligning the peakoutput of the UV source with the excitation wavelength of thephotoinitiator can be undesirable because it leads to formation of a“skin” layer that dramatically increases the viscosity of the monomermixture and progressively hinders the ability of available monomer toaccess reactive polymer chain ends. The result of this lack of access isa layer of uncured, or only partially cured, adhesive beneath the skinlayer and subsequent adhesive failure.

This technical problem can be alleviated by using a UV light source witha spectral power distribution that is offset from the primary excitationwavelength at which the photoinitiator is activated. As used herein,“offset” between the spectral power distribution and a given wavelengthmeans that the given wavelength does not overlap with wavelengths overwhich the output of the UV light source has significant intensity. In apreferred embodiment, the offset referred to above is a positive offset(i.e., the spectral power distribution spans wavelengths that are higherthan the primary excitation wavelength of the photoinitiator).

In this disclosure, the primary excitation wavelength can be defined atthe highest wavelength absorption peak (i.e., the local maximumabsorption peak located at the highest wavelength) in the UV absorptioncurve of the photoinitiator, as determined by spectroscopic measurementat a photoinitiator concentration of 0.03 wt % in acetonitrile solution.An exemplary UV absorption curve is shown in FIG. 6, which charts thenormalized absorption of light at various wavelengths by thephotoinitiator UVI-6976 by Aceto Pharma Corporation, which constitutes amixture of triarylsulfonium hexafluoroantimonate salts in propylenecarbonate/acetonitrile solution. As shown in FIG. 6, the highestwavelength absorption peak (designated with the numeral 600) is locatedat a wavelength of approximately 300 nm.

In some embodiments, the highest wavelength absorption peak is locatedat a wavelength of at most 395 nm, at most 375 nm, or at most 360 nm.

In exemplary embodiments, the difference in wavelength between thehighest wavelength absorption peak of the photoinitiator and the peakintensity of the UV light source is in the range of from 30 nm to 110nm, preferably from 40 nm to 90 nm, and more preferably from 60 nm to 80nm.

The UV radiation exposure time required to obtain sufficient activationof the photoinitiator(s) is not particularly restricted. Typically, theadhesive layer is exposed to ultraviolet radiation over an exposureperiod of at least 0.25 seconds, at least 0.35 seconds, at least 0.5seconds, or at least 1 second. The adhesive layer can be exposed toultraviolet radiation over an exposure period of at most 10 minutes, atmost 5 minutes, at most 2 minutes, at most 1 minute, or at most 20seconds.

Based on the exposure time used, the UV radiation should provide asufficient energy density to obtain a functional cure. In someembodiments, the UV radiation can deliver an energy density of at least0.5 J/cm², at least 0.75 J/cm², or at least 1 J/cm². In the same oralternative embodiments, the UV radiation can deliver an energy densityof at most 15 J/cm², at most 12 J/cm², or at most 10 J/cm².

Advantageously, the curing methods described above can enable the UVlight to cure adhesives with thicknesses greater than would normally beviable using conventional curing methods. Thicker adhesives, andparticularly foamed adhesives that can compress and/or conform whenurged against non-planar surfaces, can bridge the gap between opposingadherent surfaces. This allows the adhesive to wet out both surfaces andobtain a strong and reliable (i.e. consistent) bond.

When bonding to vehicular glass, there is often a significanttopological mismatch between the opposing surfaces of the hardware andglass to be bonded. For example, automotive windshields generally havesignificant curvature, and this curvature can vary significantly basedon the make and model of the automobile. In some applications, to obtainadequate adhesive wet out on both the hardware and the glass, theadhesive layer should have a maximum thickness of at least 0.5millimeters, at least 0.6 millimeters, or at least 1 millimeter.

Adhesive Properties

The provided adhesives, when cured, preferably have an Overlap ShearStrength (based on the test methods described herein) of at least 0.75MPa, more preferably at least 1.0 MPa, and most preferably at least 1.5MPa. Cured adhesives having a particularly high overlap shear strengthare herein referred to as structural adhesives. Structural adhesives arecured adhesives that have an Overlap Shear Strength of at least 3.5 MPa,more preferably at least 5 MPa, and most preferably at least 7 MPa.

In some embodiments, the adhesive layer 114, after curing, provides atleast one of i) an Overlap Shear Strength of at least 5 MPa, ii) aCleavage Resistance of at least 40 N, and iii) a Creep Test result of atmost 500% strain, based on the test methods described herein. In apreferred embodiment, the adhesive layer 114 provides each of i), ii),and iii).

Preferably, the adhesive layer 114, after curing, further displays aTensile Strength of at least 60 N, based on the test methods describedherein.

The provided adhesives should also have sufficient strength to holdautomotive hardware stationary against a glass substrate withoutdelaminating or sagging under gravity prior to being cured (i.e., in the“green” state). These aspects can be quantified using, for example, the90° Peel Adhesion test, Cleavage Resistance, and Creep Test.

-   Preferably, the adhesive layer 114, prior to being irradiated with    ultraviolet radiation, displays a 90° Peel Adhesion of at least 9 N    based on the test methods described herein.-   Preferably, the adhesive layer 114, prior to being irradiated with    ultraviolet radiation, displays a Cleavage Resistance of at least 40    N, at least 50 N, or at least 60 N.-   Preferably, the adhesive layer 114, prior to being irradiated with    ultraviolet radiation, displays a Creep Test result of at most 500%,    at most 300%, or at most 200%.

The provided bonding methods can be further exemplified by the followingnon-exhaustive list of embodiments:

-   1. A method of bonding some structure (e.g., hardware) to glass such    as, e.g., vehicular and/or architectural (vehicular/architectural)    glass, including: providing the glass comprising a first sheet of    glass (e.g., tempered glass), a polymeric backing, and a second    sheet of glass (e.g., tempered glass), laminated in that order via    an autoclaving process or a similar process of applied heat and    pressure over time; disposing an adhesive layer on a bonding surface    of either the structure (e.g., hardware) or the glass (e.g.,    vehicular/architectural glass), the adhesive layer including a    curable composition that is dimensionally stable at ambient    conditions; either before or after disposing the adhesive layer on    the bonding surface, irradiating the adhesive layer with ultraviolet    radiation to initiate curing of the curable composition; placing the    structure (e.g., hardware) so as to be bonded to the glass (e.g.,    vehicular/architectural glass) by the adhesive layer; and allowing    the adhesive layer to cure.-   2. The method of embodiment 1, further including heating the    adhesive layer to a temperature in the range of from about 35° C. to    about 180° C. for a period of time in the range of from 3 minutes to    35 minutes to accelerate curing of the adhesive layer.-   3. The method of embodiment 2, where the temperature is in the range    of from about 70° C. to about 150° C.-   4. The method of embodiment 3, where the temperature is in the range    of from about 90° C. to about 120° C.-   5. The method of any one of embodiments 2-4, where the period of    time is in the range of from about 2 minutes to about 25 minutes.-   6. The method of embodiment 5, where the period of time is in the    range of from about 5 minutes to about 15 minutes.-   7. The method of any one of embodiments 1-6, where the curable    composition includes: a) in the range of from about 25 to about 80    parts by weight of one or more epoxy resins; b) in the range of from    about 5 to about 30 parts by weight of one or more liquid polyether    polyols; c) in the range of from about 10 to about 50 parts by    weight of one or more hydroxyl-functional film-forming polymers or    precursors thereof, where the sum of a) to c) is 100 parts byr    weight; and d) in the range of from about 0.1 to about 5 parts of a    photoinitiator, relative to the 100 parts of a) to c).-   8. The method of embodiment 7, where the curable composition    includes: i) in the range of from about 15 to about 50 parts by    weight of a tetrahydrofurfuryl (meth)acrylate copolymer; ii) in the    range of from about 25 to about 50 parts by weight of the one or    more epoxy resin components; iii) in the range of from about 5 to    about 15 parts by weight of the one or more liquid polyether    polyols; iv) in the range of from about 10 to about 25 parts by    weight of one or more hydroxyl-functional film-forming polymers or    precursors thereof; where the sum of i) to iv) is 100 parts by    weight; and v) in the range of from about 0.1 to about 5 parts by    weight of a cationic photoinitiator, relative to the 100 parts of i)    to iv).-   9. The method of embodiment 8, where the tetrahydrofurfuryl    (meth)acrylate copolymer includes: A) in the range of from about 40    to about 60 wt % of tetrahydrofurfuryl (meth)acrylate; B) in the    range of from about 40 to about 60 wt % of C₁-C₈ alkyl    (meth)acrylate esters; and C) in the range of from 0 to about 10 wt    % of cationically reactive functional monomers, where the sum of    A)-C) is 100 wt %.-   10. The method of any one of embodiments 1-6, where the curable    composition includes: a) in the range of from about 15 to about 50    parts by weight of a semi-crystalline polyester resin; b) in the    range of from about 20 to about 75 parts by weight of one or more    epoxy resins; c) in the range of from about 5 to about 15 parts by    weight of one or more liquid polyether polyols; d) in the range of    from about 5 to about 20 parts by weight of one or more    hydroxyl-functional film-forming polymers and precursors thereof,    where the sum of a) to d) is 100 parts by weight; and e) in the    range of from about 0.1 to about 5 parts by weight of a    photoinitiator, relative to the 100 parts of a) to d).-   11. The method of any one of embodiments 1-10, where the    photoinitiator has an ultraviolet absorption curve characterized by    a highest wavelength absorption peak measured at a concentration of    about 0.03 wt % in acetonitrile solution and where the ultraviolet    radiation has a spectral power distribution positively offset from    the wavelength of the highest wavelength absorption peak.-   12. The method of embodiment 11, where the spectral power    distribution has a peak intensity at a wavelength in the range of    from about 315 nm to about 400 nm.-   13. The method of embodiment 12, where the spectral power    distribution has a peak intensity at a wavelength in the range of    from about 350 nm to about 380 nm.-   14. The method of any one of embodiments 11-13, where the spectral    power distribution substantially excludes wavelengths below about    280 nm.-   15. The method of embodiment 14, where the spectral power    distribution substantially excludes wavelengths below about 290 nm.-   16. The method of embodiment 15, where the spectral power    distribution substantially excludes wavelengths below about 300 nm.-   17. The method of any one of embodiments 11-16, where the highest    wavelength absorption peak is located at a wavelength of at most    about 395 nm.-   18. The method of embodiment 17, where the highest wavelength    absorption peak is located at a wavelength of at most about 375 nm.-   19. The method of embodiment 18, where the highest wavelength    absorption peak is located at a wavelength of at most about 360 nm.-   20. The method of any one of embodiments 11-19, where the    ultraviolet radiation is generated by a light emitting diode source.-   21. A method of bonding a structure (e.g., hardware) to glass (e.g.,    vehicular/architectural glass), including: disposing an adhesive    layer on a bonding surface of either the hardware or the    vehicular/architectural glass, the adhesive layer including a    curable composition comprised of: a) in the range of from about 25    to about 80 parts by weight of one or more epoxy resins; b) in the    range of from about 5 to about 30 parts by weight of one or more    liquid polyether polyols; c) in the range of from about 10 to about    50 parts by weight of one or more hydroxyl-functional film-forming    polymers and precursors thereof, where the sum of a) to c) is 100    parts per weight; and d) in the range of from about 0.1 to about 5    parts by weight of a photoinitiator, relative to the 100 parts of a)    to c); either before or after disposing the adhesive layer on the    bonding surface, irradiating the adhesive layer with ultraviolet    radiation to initiate curing of the curable composition; placing the    structure (e.g., hardware) so as to be bonded to the glass (e.g.,    vehicular/architectural glass) by the adhesive layer; and allowing    the adhesive layer to cure.-   22. The method of embodiment 21, where the curable composition    includes about 55 to about 80 parts by weight of the one or more    epoxy resins.-   23. The method of embodiment 21 or 22, where the curable composition    includes about 10 to about 30 parts by weight of the one or more    liquid polyether polyols.-   24. The method of any one of embodiments 21-23, where the curable    composition includes in the range of from about 20 to about 35 parts    by weight of the one or more hydroxyl-functional film-forming    polymers and precursors thereof.-   25. A method of bonding a structure (e.g., hardware) to glass (e.g.,    vehicular/architectural glass), including: disposing an adhesive    layer on a bonding surface of either the hardware or the    vehicular/architectural glass, the adhesive layer including a    curable composition comprised of: a) in the range of from about 1 to    about 50 parts by weight of one or more resins selected from    (meth)acrylate resins; b) in the range of from about 12 to about 40    parts by weight of one or more hydroxyl-functional film-forming    polymers and precursors thereof; c) in the range of from about 20 to    about 75 parts by weight of one or more epoxy resins; d) in the    range of from about 10 to about 30 parts by weight of one or more    polyether polyols, where the sum of a) to d) is 100 parts by weight;    and e) in the range of from about 0.1 to about 5 parts by weight of    a photoinitiator, relative to the 100 parts of a) to d); either    before or after disposing the adhesive layer on the bonding surface,    irradiating the adhesive layer with ultraviolet radiation to    initiate curing of the curable composition; placing the structure    (e.g., hardware) so as to be bonded to the glass (e.g.,    vehicular/architectural glass) by the adhesive layer; and allowing    the adhesive layer to cure.-   26. The method of embodiment 25, where the curable composition    includes: i) in the range of from about 15 to about 50 parts by    weight of a tetrahydrofurfuryl (meth)acrylate copolymer; ii) in the    range of from about 25 to about 50 parts by weight of the one or    more epoxy resins; iii) in the range of from about 5 to about 15    parts by weight of the one or more liquid polyether polyols; iv) in    the range of from about 10 to about 25 parts by weight of one or    more hydroxyl-functional film-forming polymers and precursors    thereof, where the sum of i) to iv) is 100 parts by weight; and v)    in the range of from about 0.1 to about 5 parts by weight of a    cationic photoinitiator, relative to the 100 parts of i) to iv).-   27. The method of embodiment 26, where the tetrahydrofurfuryl    (meth)acrylate copolymer includes: A) in the range of from about 40    to about 60 wt % of tetrahydrofurfuryl (meth)acrylate; B) in the    range of from about 40 to about 60 wt % of C₁-C₈ alkyl    (meth)acrylate ester; and C) in the range of from 0 to about 10 wt %    of cationically reactive functional monomer, where the sum of A)-C)    is 100 wt %.-   28. A method of bonding a structure (e.g., hardware) to glass (e.g.,    vehicular/architectural glass), including: disposing an adhesive    layer on a bonding surface of either the hardware or the    vehicular/architectural glass, the adhesive layer including a    curable composition comprised of: a) in the range of from about 15    to about 50 parts by weight of a semi-crystalline polyester    resin; b) in the range of from about 20 to about 75 parts by weight    of one or more epoxy resins; c) in the range of from about 5 to    about 15 parts by weight of one or more liquid polyether polyols; d)    in the range of from about 5 to about 20 parts by weight of one or    more hydroxyl-functional film-forming polymers and precursors    thereof, where the sum of a) to d) is 100 parts by weight; and e) in    the range of from about 0.1 to about 5 parts by weight of a    photoinitiator, relative to the 100 parts of a) to d); either before    or after disposing the adhesive layer on the bonding surface,    irradiating the adhesive layer with ultraviolet radiation to    initiate curing of the curable composition, where the photoinitiator    has an ultraviolet absorption curve characterized by a highest    wavelength absorption peak measured at a concentration of 0.03 wt %    in acetonitrile solution and where the ultraviolet radiation has a    spectral power distribution positively offset from the wavelength of    the highest wavelength absorption peak; placing the structure (e.g.,    hardware) so as to be bonded to the glass (e.g.,    vehicular/architectural glass) by the adhesive layer; and allowing    the adhesive layer to cure.-   29. The method of any one of embodiments 21-28, where the one or    more hydroxy-functional film forming polymers are selected from    phenoxy resins, ethylene-vinyl acetate copolymers, polycaprolactone    polyols, polyester polyols, and polyvinyl acetal resins.-   30. The method of any one of embodiments 21-27, where the    photoinitiator has an ultraviolet absorption curve characterized by    a highest wavelength absorption peak measured at a concentration of    about 0.03 wt % in acetonitrile solution and where the ultraviolet    radiation has a spectral power distribution positively offset from    the wavelength of the highest wavelength absorption peak.-   31. The method of embodiment 28 or 30, where the spectral power    distribution has a peak intensity at a wavelength in the range of    from about 315 nm to about 400 nm.-   32. The method of embodiment 31, where the spectral power    distribution has a peak intensity at a wavelength in the range of    from about 350 nm to about 380 nm.-   33. The method of any one of embodiments 28 and 30-32, where the    spectral power distribution substantially excludes wavelengths below    about 280 nm.-   34. The method of embodiment 33, where the spectral power    distribution substantially excludes wavelengths below about 290 nm.-   35. The method of embodiment 34, where the spectral power    distribution substantially excludes wavelengths below about 300 nm.-   36. The method of any one of embodiments 28 and 30-35, where the    highest wavelength absorption peak is located at a wavelength of at    most about 395 nm.-   37. The method of embodiment 36, where the highest wavelength    absorption peak is located at a wavelength of at most about 375 nm.-   38. The method of embodiment 37, where the highest wavelength    absorption peak is located at a wavelength of at most about 360 nm.-   39. The method of any one of embodiments 28 and 30-38, where the    ultraviolet radiation is generated by a light emitting diode source    that emits monochromatic light.-   40. A method of bonding a structure (e.g., hardware) to glass (e.g.,    vehicular/architectural glass), including: disposing an adhesive    layer on a bonding surface of either the hardware or the    vehicular/architectural glass, the adhesive layer including a    photoinitiator having an ultraviolet absorption curve characterized    by a highest wavelength absorption peak measured at a concentration    of about 0.03 wt % in acetonitrile solution; either before or after    disposing the adhesive layer on the bonding surface, irradiating the    adhesive layer with ultraviolet radiation to initiate curing of the    curable composition, where the ultraviolet radiation has a spectral    power distribution positively offset from the wavelength of the    highest wavelength absorption peak; placing the structure (e.g.,    hardware) so as to be bonded to the glass (e.g.,    vehicular/architectural glass) by the adhesive layer; and allowing    the adhesive layer to cure.-   41. The method of embodiment 40, where the spectral power    distribution has a peak intensity at a wavelength in the range of    from about 315 nm to about 400 nm.-   42. The method of embodiment 41, where the spectral power    distribution has a peak intensity at a wavelength in the range of    from about 350 nm to about 380 nm.-   43. The method of any one of embodiments 40-42, where the spectral    power distribution substantially excludes wavelengths below about    280 nm.-   44. The method of embodiment 43, where the spectral power    distribution substantially excludes wavelengths below about 290 nm.-   45. The method of embodiment 44, where the spectral power    distribution substantially excludes wavelengths below about 300 nm.-   46. The method of any one of embodiments 40-45, where the highest    wavelength absorption peak is located at a wavelength of at most    about 395 nm.-   47. The method of embodiment 46, where the highest wavelength    absorption peak is located at a wavelength of at most about 375 nm.-   48. The method of embodiment 47, where the highest wavelength    absorption peak is located at a wavelength of at most about 360 nm.-   49. The method of any one of embodiments 40-48, where the    ultraviolet radiation is generated by a light emitting diode source.-   50. The method of any one of embodiments 40-49, where the adhesive    layer has a maximum thickness of at least about 0.5 millimeters.-   51. The method of embodiment 50, where the adhesive layer has a    maximum thickness of at least about 0.6 millimeters.-   52. The method embodiment 51, where the adhesive layer has a maximum    thickness of at least about 1 millimeters.-   53. The method of any one of embodiments 1-52, where the adhesive    layer is a die-cut adhesive layer.-   54. The method of any one of embodiments 1-53, where the adhesive    layer is exposed to the ultraviolet radiation over an exposure    period in the range of from about 0.25 seconds to about 10 minutes.-   55. The method of embodiment 54, where the adhesive layer is exposed    to the ultraviolet radiation over an exposure period in the range of    from about 0.5 seconds to about 2 minutes.-   56. The method of embodiment 55, where the adhesive layer is exposed    to the ultraviolet radiation over an exposure period in the range of    from about 0.5 second to about 20 seconds.-   57. The method of any one of embodiments 1-56, where the ultraviolet    radiation delivers an energy density in the range of from about 0.5    to about 15 J/cm².-   58. The method of embodiment 57, where the ultraviolet radiation    delivers an energy density in the range of from about 1 to about 10    J/cm².-   59. The method of any one of embodiments 1-58, where the adhesive    layer further includes a fiber reinforcement layer.-   60. The method of embodiment 59, where the fiber reinforcement layer    includes a woven scrim.-   61. The method of any one of embodiments 1-60, where the adhesive    layer, prior to being irradiated with the ultraviolet radiation,    displays a 90° Peel Adhesion of at least about 9 N and a Creep Test    result of at most about 500%.-   62. The method of embodiment 61, where the adhesive layer, prior to    being irradiated with the ultraviolet radiation, displays a Creep    Test result of at most about 200%.-   63. The method of any one of embodiments 1-62, where the adhesive    layer, subsequent to being irradiated with the ultraviolet    radiation, displays an Overlap Shear Strength of at least about 5    MPa, a Cleavage Resistance of at least about 40 N, and a Tensile    Strength of at least about 60 N.-   64. The method of embodiment 63, where the adhesive layer,    subsequent to being irradiated with the ultraviolet radiation,    displays a Cleavage Resistance of at least about 60 N.-   65. The method of any one of embodiments 1-64, where the curable    composition includes a photoacid generator.-   66. The method of embodiment 65, where the photoacid generator    includes a triarylsulfonium hexafluoroantimonate salt or    triarylsulfonium hexafluorophosphate salt.-   67. The method of any one of embodiments 11-20, 28, and 30-52,    wherein the wavelength of the highest wavelength absorption peak    coincides with the primary excitation wavelength of the    photoinitiator.-   68. A method of bonding an article to a substrate, including:    disposing an adhesive layer on a bonding surface of either the    article or the substrate, the adhesive layer including a    photoinitiator having an ultraviolet absorption curve characterized    by a highest wavelength absorption peak measured at a concentration    of about 0.03 wt % in acetonitrile solution; either before or after    disposing the adhesive layer on the bonding surface, irradiating the    adhesive layer with ultraviolet radiation to initiate curing of the    curable composition, where the ultraviolet radiation has a spectral    power distribution positively offset from the wavelength of the    highest wavelength absorption peak; placing the article so as to be    bonded to the substrate by the adhesive layer; and allowing the    adhesive layer to cure.-   69. The method of embodiment 68, where the difference in wavelength    between the highest wavelength absorption peak of the photoinitiator    and the peak intensity of the UV light source is in the range of    from about 30 nm to about 110 nm.-   70. The method of embodiment 69, where the magnitude of the offset    is in the range of from about 40 nm to about 90 nm.-   71. The method of embodiment 70, where the magnitude of the offset    is in the range of from about 60 nm to about 80 nm.

EXAMPLES

Objects and advantages of this disclosure are further illustrated by thefollowing non-limiting examples. Particular materials and amountsthereof recited in these examples, as well as other conditions anddetails, are not intended to be limiting on this disclosure. Unlessotherwise noted, all parts, percentages, ratios, etc. in the Examplesand the rest of the specification are by weight.

Test Methods Overlap Shear Strength Test

The adhesion of the compositions to e-coated steel was determined bymeasuring the overlap shear strength of bonded specimens. Substratecoupons measuring 25 mm×50.8 mm were wiped with a 1:1 (v:v) solution ofisopropyl alcohol and water and were allowed to air-dry. Release linerwas removed from one side of a 12.7 mm×25 mm portion of the adhesivecomposition and the composition was applied to one coupon. Unlessotherwise specified, the second release liner was removed and thecomposition was exposed to a microwave source (H-bulb, HERAEUSNOBLELIGHT AMERICA, Gaithersburg, Md., 0.9-1.2 J/cm² UVA, as measured bya UVICURE Plus Integrating Radiometer (EIT, Inc., Sterling, Va.)) or 365nm LED source (CLEARSTONE TECHNOLOGIES, Hopkins, Minn., 7.1 J/cm² UVA asmeasured by a Power Puck® II radiometer (EIT, Inc., Sterling, Va.)). Asecond coupon was applied to the irradiated sample thus closing thebond. Unless otherwise specified, the assembly was laminated by means ofapplying a static 6 kg load to the specimen for 30-60 s. Specimens wereallowed to cure at ambient temperature and humidity for 24 hours priorto testing. A dynamic overlap shear test was performed at ambienttemperature using an INSTRON Tensile Tester Model 5581 (INSTRON CORP.,Canton, Mass.). Test specimens were loaded into the grips and thecrosshead was operated at 2.5 mm per minute, loading the specimen tofailure. Stress at break was recorded in units of MPa.

Cleavage Test

The adhesion of plastic material to glass was determined by measuringthe cleavage strength of bonded specimens. Plastic test pieces, made ofthe specified material, measuring 22 mm×28 mm×4 mm, and tempered glassplaques, measuring 127 mm×50 mm×4 mm were wiped with a 1:1 (v:v)solution of isopropyl alcohol and water and were allowed to air-dry. Arelease liner was removed from a 22 mm×28 mm portion of the adhesivecomposition and this portion was applied to the plastic test piece.Unless otherwise specified, lamination was accomplished by means ofapplying a 1-3 kg weight to the test piece for 30 s. The second releaseliner was removed and the adhesive portion was exposed to a microwavesource (H-bulb, HERAEUS NOBLELIGHT AMERICA, Gaithersburg, Md., 0.9-1.2J/cm² UVA, as measured by a UVICURE Plus Integrating Radiometer (EIT,Inc., Sterling, Va.) or 365 nm LED source (CLEARSTONE TECHNOLOGIES,Hopkins, Minn., 7.1 J/cm² UVA as measured by a Power Puck® II radiometer(EIT, Inc., Sterling, Va.). The irradiated sample was applied to atempered glass plaque and laminated by applying a 6 kg weight to thebonded assembly for 30-60 s. The assembly was allowed to cure 24 hoursunder ambient conditions prior to testing. Cured assemblies were mountedvertically (i.e., with the plane of the bond in a vertical orientation)in an INSTRON Tensile Tester Model 5565 (INSTRON CORP., Canton, Mass.).A 70 mm lever arm is attached to the plastic test piece, perpendicularto the plane of the bond and is pulled upwardly (parallel to the planeof the bond) at a rate of 2.5 mm per minute. The maximum value at breakwas recorded in N.

90° Peel Adhesion Test

Adhesive properties of the compositions were determined by measuring the90° Peel adhesion. A stainless steel plate measuring 101 mm×127 mm wascleaned by wiping with a 1:1 (v:v) solution of isopropyl alcohol andwater and was allowed to air-dry. Release liner was removed from oneside of a 127 mm×12.7 mm portion of the adhesive composition and thecomposition was applied to the steel plate. The second release liner wasremoved and a 159 mm×16 mm strip of aluminum foil was placed over theadhesive with the anodized side in contact with the adhesive. Theadhesive was laminated by means of a metal roller weighing 6.8 kg. Aftera dwell time of 20 minutes at ambient temperature, the 90° Peel Adhesionwas measured using an INSTRON Tensile Tester Model 5565 (INSTRON CORP.,Canton, Mass.) at a peel speed of 305 mm per minute. The average 90°Peel adhesion was recorded in units of N.

Tensile Pluck Test

The adhesion of plastic material to glass was determined by measuringthe tensile strength of bonded specimens. Plastic test pieces, made ofthe specified material, measuring 22 mm×28 mm×4 mm, and tempered glassplaques, measuring 127 mm×50 mm×4 mm were wiped with a 1:1 (v:v)solution of isopropyl alcohol:water and were allowed to dry in air.Release liner was removed from a 22 mm×28 mm portion of the adhesivecomposition and this portion was applied to the plastic test piece.Lanination was accomplished by means of applying a 1-3 kg weight to thetest piece for 30 s. Unless otherwise specified, the second releaseliner was removed and the adhesive portion was exposed to a microwavesource (H-bulb, HERAEUS NOBLELIGHT AMERICA, Gaithersburg, Md., 0.9-1.2J/cm² UVA, as measured by a UVICURE Plus Integrating Radiometer (EIT,Inc., Sterling, Va.)). Unless otherwise specified, the irradiated samplewas applied to a tempered glass plaque and laminated by applying a 6 kgweight to the bonded assembly for 30-60 s. The assembly was allowed tocure 24 hours under ambient conditions prior to testing. Curedassemblies were mounted horizontally in an INSTRON Tensile Tester Model5565 (INSTRON CORP., Canton, Mass.). A 70 mm arm is attached to theplastic test piece and is pulled upwardly (perpendicular to the plane ofthe bond) at a rate of 12.7 mm per minute. The load at break wasrecorded in N.

Parallel Torque Test

The Parallel Torque test is a test of how well a bracket or otherhardware adheres to glass, and how much bond strength it has underparallel torque. A lever, such as a torque-wrench, with a fixturecompatible with a test piece, is slowly turned in a plane parallel tothe bonded area. Torque was recorded in N-m. Plastic test pieces, madeof the specified material, measuring 22 mm×28 mm×4 mm, and fit-glassplaques, measuring 100 mm×100 mm×5 mm were wiped with a 1:1 (v:v)solution of isopropyl alcohol:water and were allowed to dry in air. Arelease liner was removed from a 22 mm×28 mm portion of the adhesivecomposition and this portion was applied to the plastic test piece.Lamination was accomplished by applying 138 kPa (20 psi) for 6 sec tothe test piece and adhesive composition construction. Unless otherwisespecified, the second release liner was removed and the composition wasexposed to a microwave source (H-bulb, HERAEUS NOBLELIGHT AMERICA,Gaithersburg, Md., 0.9-1.2 J/cm² UVA, as measured by a UVICURE PlusIntegrating Radiometer (EIT, Inc., Sterling, Va.)) or 365 nm LED source(CLEARSTONE TECHNOLOGIES, Hopkins, Minn., 7.1 J/cm² UVA as measured by aPower Puck® II radiometer (EIT, Inc., Sterling, Va.)). The irradiatedsample was then applied to glass substrate to close the bond. Theassembly was laminated by applying 207 kPa (30 psi) for 6 sec to thetest piece, adhesive composition, and glass construction. Specimens wereeither cured under ambient conditions for 24 hours, or postbaked at thespecified temperature for the specified period of time, followed byconditioning at ambient temperature and humidity for 24 hours prior totesting.

Vertical Torque Test

The Vertical Torque Test is a test of how well a bracket or otherhardware adheres to glass, and how much bond strength it has undervertical torque. A lever, such as a torque-wrench, with a fixturecompatible with a test piece, is slowly turned in a plane perpendicularto the bonded area while maintaining a downward pressure at the front ofthe button. The torque is recorded in N-m. The torque wrench has amaximum detection limit of 813 N-m. Plastic test pieces, made of thespecified material, measuring 22 mm×28 mm×4 mm, and frit-glass plaques,measuring 100 mm×100 mm×5 mm were wiped with a 1:1 (v:v) solution ofisopropyl alcohol and water and were allowed to air-dry. Release linerwas removed from a 22 mm×28 mm portion of the adhesive composition andthis portion was applied to the plastic test piece. Lamination wasaccomplished by applying 138 kPa (20 psi) for 6 sec to the test pieceand adhesive composition construction. Unless otherwise specified, thesecond release liner was removed and the composition was exposed to amicrowave source (H-bulb, HERAEUS NOBLELIGHT AMERICA, Gaithersburg, Md.,0.9-1.2 J/cm² UVA, as measured by a UVICURE Plus Integrating Radiometer(EIT, Inc., Sterling, Va.)) or 365 nm LED source (CLEARSTONETECHNOLOGIES, Hopkins, Minn., 7.1 J/cm² UVA as measured by a Power Puck®II radiometer (EIT, Inc., Sterling, Va.)). The irradiated sample werethen applied to glass substrate to close the bond. The assembly waslaminated by applying 207 kPa (30 psi) for 6 sec to the test piece,adhesive composition, and glass construction. Specimens were eithercured under ambient conditions for 24 hours, or postbaked at thespecified temperature for the specified period of time, followed byconditioning at ambient temperature and humidity for 24 hours prior totesting.

Rheology Test

The glass transition temperature (T_(g)) of the acrylic copolymers wasdetermined using an MCR 302 rheometer (ANTON PAAR GmbH, Graz, Austria)operating in oscillatory mode. Samples were loaded onto 8 mm parallelplates and a normal force of 0.1 N was applied. The sample was firstcooled from 30° C. to −50° C. at 10° C. per minute while the strain (γ)was reduced from 1-0.01% and the normal force (F_(N)) was increased from0.1-0.5 N. The sample was then analyzed while heating from −50° C. to150° C. at 10° C. per minute while y was increased from 0.01-5% andF_(N) was reduced from 0.5-0.05 N. The oscillatory frequency (F) was 1Hz in all experiments. The temperature coinciding with the primary peakin tan(δ) was recorded as the T_(g), and is given in units of ° C.

Attenuated Total Reflectance (FTIR-ATR)

Attenuated total reflectance (ATR) measurements were made on a NicoletNexus 670 IR Spectrometer (THERMO FISHER SCIENTIFIC INC., Waltham,Mass.) with MCT/A detector and Smart OMNI single-bounce germanium (Ge)ATR accessory. Spectra consisted of thirty-two scans with a resolutionof four (data spacing=2 cm⁻¹) over the range of 4000-650 cm⁻¹. ATRspectra were taken on samples both before (“Initial”) and after(“Exposed”) specified cure profiles (H-bulb, 70° C., 10 min; H-bulb, 24hr, RT; 365 nm LED, 24 hr, RT; or 180° C., 30 min). For “H bulb, 70° C.,10 min” samples, the top liner was removed and the adhesive exposed totwo passes at 10 meters/min (32 fpm) from a Fusion Light Hammer® 10equipped with H bulb (HERAEUS NOBLELIGHT AMERICA; Gaithersburg, Md.).This corresponded to a total exposure of 1 UVA, 1 UVB, 0.25 UVC, 1.1 UVV(J/cm²) as measured by a Power Puck® II radiometer (EIT, Inc., Sterling,Va.). The release liner was re-applied and the sample placed in a 70° C.oven for 10 min prior to ATR. “H-bulb, 24 hr, RT” samples received thesame UV exposure as above, but were instead held at room temperature(approximately 21° C.) for 24 hours prior to ATR. For “365 nm LED, 24hr, RT” samples, the top liner was removed and the adhesive exposed toone pass at 0.6 meters/min (2 fpm) from a 365 nm LED (CLEARSTONETECHNOLOGIES, Hopkins, Minn.). This corresponded to a total exposure of7.6 J/cm² (1.2 W/cm²) as measured by a UViCure® Plus radiometer (EIT,Inc., Sterling, Va.). The release liner was re-applied and the sampleheld at room temperature (ca. 21° C.) for 24 hours prior to ATR. Foreach ATR measurement, the release liner was peeled from one side of thetape sample. The resulting adhesive surface was pressed down into goodcontact with the Ge crystal for the duration of the spectrumacquisition. Afterwards, the sample was peeled from the Ge crystal, thecrystal cleaned with ethyl acetate, and a new background taken beforethe next measurement. The size of the 910 cm⁻¹ absorbance was monitoredas an indicator of epoxy conversion, by comparing “Initial” vs.“Exposed” spectra of the same UVi-SBT composition. Samples weredesignated Uncured (U) if the 910 cm⁻¹ peak was unchanged, Partial Cure(P) if the peak was diminished but still visible, or Cured (C) if nodiscernible peak remained. Spectra for both faces (front and back) ofexposed UVi-SBTs were obtained and analyzed, where ‘front’ was thedirectly-irradiated side and ‘back’ was the side indirectly exposedthrough the thickness of the tape. Results are reported in Tables 2, 4 &6 below.

Creep Test

The creep performance and dimensional stability of compositions wasdetermined using an MCR 302 rheometer (ANTON PAAR GmbH, Graz, Austria).A 0.6 mm thick sample of each composition was loaded between 25 mmparallel plates and a normal force (F_(N)) of 1 N was applied. Aconstant stress of 1000 Pa was applied for 300 s, then a constant stressof 0 Pa was applied for 600 s. The strain at 300 s (γ₃₀₀ _(s) ) wasrecorded to characterize the creep behavior, or cold-flow of thecomposition and is given in % strain.

Windshield Adhesion Test

The windshield adhesion test is a measure of how well and adhesivecomposition adheres to a laminated or tempered glass assembly. A portionof laminated vehicular glass and a 20 mm aluminum dolly were cleanedprior to bonding by wiping with a 1:1 (v:v) solution of isopropylalcohol and water and were allowed to air-dry. A portion of the adhesivecomposition was cut to the size of the dolly. The release liner wasremoved from one side and the sample was applied to the dolly. Thesecond release liner was removed and the specimen was exposed using a365 nm LED (7.6 J/cm² UVA, CLEARSTONE TECHNOLOGIES, Hopkins, Minn., asmeasured by an EIT UV Power Puck II, EIT, Sterling, Va.). The adhesiveand dolly construct was applied to the laminated glass usinghand-pressure. Test specimens were allowed to cure at ambienttemperature and humidity and were then tested by the following method atthe specified time interval.

The bond strength was determined with a PosiTest AT-A adhesion tester(DeFelsko Corp., Ogdensburg, N.Y.) according to ASTM D 4541 “StandardTest Method for Pull-Off Strength of Coatings Using Portable AdhesionTesters.” The bond strength was tested with a pressure rate of 0.2MPa/s, and value recorded in MPa at bond failure.

Materials

ARCOL LHT 240 Polyether polyol obtained from Bayer MaterialScience LLC.EPON 1001F Solid epoxy resin comprised of diglycidyether of bisphenol Aobtained from Momentive Specialty Chemicals, Inc. EPON 828 Liquid epoxyresin comprised of diglycidyether of bisphenol A obtained from MomentiveSpecialty Chemicals, Inc. EPONEX 1510 Liquid epoxy resin comprised ofdiglycidyether of hydrogenated bisphenol A obtained from MomentiveSpecialty Chemicals, Inc. LEVAPREN 700HV Ethylene-vinyl acetatecopolymer obtained from Lanxess Corporation. PHENOXY PKHA Phenoxy resinobtained from InChem Corporation. DYNACOLL S EP 1408 Semi-crystallinepolyester polyol obtained from Evonik. DYNACOLL S 1426 Amorphouspolyester polyol obtained from Evonik. UVI 6976 Triaryl-sulfoniumHexafluoroantimonate, 50 wt % in propylene carbonate obtained from AcetoPharma Corporation. GPTMS 3-(Glycidoxypropyl) Trimethoxysilane obtainedfrom UCT, Inc., Bristol, PA. 4-HBA 4-Hydroxybutyl acrylate obtained fromSan Esters, New York City, NY. PAG210S Triarylsulfonium salt withproprietary phosphate anion obtained from San-Apro Ltd., Tokyo, Japan.Propylene carbonate (PC) Solvent obtained from Sigma-Aldrich, St. Louis,MO. Methyl acrylate (MA) Monomer obtained from Florham Park, NJ.1,4-Cyclohexanedimethanol Polyol obtained from Sigma-Aldrich.1,6-Hexanediol Diol obtained from Sigma-Aldrich. Butyl acrylate (BA)Monomer obtained from BASF. Glycidyl methacrylate Monomer obtained fromDow Chemical (GMA) Company. IRGACURE 651 Benzyldimethyl ketalphotoinitiator obtained from BASF. Iso-octyl thioglycolate Obtained fromEvans Chemetics LP, (IOTG) Teaneck, NJ. Phenoxyethyl acrylatePhenoxyethyl acrylate (Viscoat #192) (2-POEA) obtained from San Esters.Isobornyl acrylate (IBOA) Isobornyl acrylate (IBXA) obtained from SanEsters. Tetrahydrofurfuryl acrylate Tetrahydrofurfuryl acrylate (V-150)(THFa) obtained from San Esters. CRASTIN test pieces 30%glass-reinforced polybutylene terephthalate (PBT), obtained from DuPont,Wilmington, DE, under the trade designation “LW9030 BK851.” GRIVORY testpieces 50% glass-fibre reinforced copolyamide thermoplastic materialobtained from EMS- Grivory, Sumter, SC. Tempered glass Clear temperedglass obtained from Industrial Glass Products, Los Angeles, CA. Fritglass Tempered glass plaques coated with Ferro 24-8537 frit obtainedfrom AGC Automotive, Americas, Ypsilanti, MI. Laminated vehicular glassCarlite (R) laminated glass coated with Johnson Matthey 2L5350 UV695frit obtained from Carlex Glass Co., Nashville, TN. Aluminum oxideEckart Aluminum 120 Atomized powder obtained from Eckart AmericaCorporation, Painesville, OH. E-coated steel panel Cold-rolled steel(C710 C20 DTW unpolished) with ED-5050B coating, ACT Laboratories Inc.,Hillsdale, MI.

Examples 1-3

Epoxy-EVA-based curable adhesive compositions (shown in Table 1) wereprepared using a BRABENDER mixer (C. W. BRABENDER, Hackensack, N.J.)equipped with a 50 or 250 g capacity heated mix head and kneadingelements. The mixer was operated at the desired mixing temperature of120-150° C. and the kneading elements were operated at 100 rpm. TheLEVAPREN was added to the mixer and allowed to mix for several minutes.The solid epoxy resin and phenoxy resin were then added and allowed tomix until the resins were uniformly distributed through the mixture. Theliquid epoxy resin, polyol, and silane materials were added slowly untilthey were uniformly distributed. The resulting mixture was allowed tostir for several minutes then the photoacid generator was addeddrop-wise. The mixture was allowed to stir several minutes and was thentransferred to an aluminum pan and allowed to cool. The mixture ofmaterial was placed between two release liners and was pressed, withheating to 95° C., into 0.6 mm thick film by means of a hydraulic press(CARVER INC., Wabash, Ind.).

TABLE 1 (all numbers in wt %) Material Example 1 Example 2 Example 3EPON 828 30 27 32 EPON 1001F 30 22 11 ARCOL 240 LHT 10 10 GPTMS 1LEVAPREN 700HV 30 30 42 PHENOXY PKHA 10 UVI 6976 0.5 1 1 Aluminum oxide15

Test specimens were prepared for evaluation of overlap shear, cleavageand tensile pluck performance of the cured epoxy-EVA-based compositions.Test specimens were cured by applying a portion of the composition toone substrate, irradiating with either a microwave or LED source,closing the bond, and allowing the specimen to cure as specified.Cleavage and tensile pluck specimens were prepared using CRASTIN testpieces and tempered glass. FTIR-ATR was used to determine the extent ofcure on both faces. The similarity of the uncured compositions to thoseof a pressure sensitive adhesive was determined by measuring the 90°peel adhesion and creep behavior. Results are reported in Table 2 below.

TABLE 2 Test Method Example 1 Example 2 Example 3 Overlap Shear (MPa)H-bulb, 24 hr, RT 8.3 12.3 0.4 365 nm LED, 24 hr, RT 10.6 17.2 0.3Cleavage (N) H-bulb, 24 hr, RT 191 51 27 365 nm LED, 24 hr, RT 85 59 20FTIR-ATR H-bulb, 70° C., 10 min C/C C/C C/U H-bulb, 24 hr, RT P/P P/PC/U 365 nm LED, 24 hr, RT P/P C/C C/U 90 deg peel (N) 24 31 22 Creep (%strain) 92 37 48 Tensile Pluck (N) H-bulb, 24 hr, 25° C. 693 324 —H-bulb, 24 hr, 70° C. 644 671 —

Examples 4-7

Epoxy-polyester-based curable adhesive compositions (shown in Table 3)were prepared using a BRABENDER mixer (C. W. Brabender, Hackensack,N.J.) equipped with a 50 or 250 g capacity heated mix head and kneadingelements. The mixer was operated at the desired mixing temperature of120-150° C. and the kneading elements were operated at 100 rpm. Thepolyester resin was added and allowed to mix for several minutes. Thesolid epoxy resin and phenoxy resin were added and allowed to mix untilthe resins were uniformly distributed through the mixture. The liquidepoxy resin and polyol were added slowly until uniformly distributed.The resulting mixture was allowed to stir for several minutes then thephotoacid generator was added drop-wise. The mixture was allowed to stirfor several minutes and was then transferred to an aluminum pan andallowed to cool. The material mixture was placed between two releaseliners and was pressed, with heating to 95° C., into 0.6 mm thick filmby means of a hydraulic press (Carver Inc., Wabash, Ind.).

TABLE 3 (all numbers in wt %) Material Example 4 Example 5 Example 6Example 7 EPON 828 27 15 15 27 EPON 1001F 22 29 29 22 ARCOL 240 LHT 1015 15 10 DYNACOLL S 30 40 1426 DYNACOLL S EP 40 30 1408 PHENOXY PKHA 1010 UVI 6976 1 1 1 1

Test specimens were prepared for evaluation of the overlap shear,cleavage and tensile pluck performance of the curedepoxy-polyester-based compositions. Test specimens were cured byapplying a portion of the composition to one substrate, irradiating witheither a microwave or LED source, closing the bond, and allowing thespecimen to cure as specified. Cleavage and tensile pluck specimens wereprepared using CRASTIN test pieces and tempered glass. FTIR-ATR was usedto determine the extent of cure on both faces. The adhesive propertiesof uncured compositions Examples 4-7 were determined by measuring the90° peel adhesion and creep behavior. Results are reported in Table 4below.

TABLE 4 Test Method Example 4 Example 5 Example 6 Example 7 OverlapShear (MPa) H-bulb, 24 hr, RT 1.3 2.1 1.0 3.1 365 nm LED, 24 hr, 1.2 0.411.6 21.5 RT Cleavage (N) H-bulb, 24 hr, RT 55 33 44 53 365 nm LED, 24hr, 24 22 90 50 RT FTIR-ATR H-bulb, 70° C., 10 min C/P C/P C/P C/PH-bulb, 24 hr, RT P/U P/P C/P C/P 365 nm LED, 24 hr, P/P C/C C/C C/C RT90° peel (N) 36 13 2 7 Creep (% strain) 22 16 1298 275 Tensile Pluck (N)H-bulb, 24 hr, 25° C. — — — 307 H-bulb, 24 hr, 70° C. — — — 142

Preparatory Acrylic Mixtures P1-P2

Acrylic mixtures as shown in Table 5 below were prepared for use inExamples 8-9. The mixtures were prepared as generally taught in U.S.Pat. No. 5,721,289 (Karim et. al.). For each composition, all acrylicmonomers and 0.04 parts IRGACURE 651 photoinitiator were mixed in aglass jar. For P1 only, 29 parts EPON 828 and 10 parts EPON 1001F wereadditionally added. The solutions were purged with nitrogen and exposedto UVA light with stirring until the viscosity of the mixture wassuitable for coating (500-5000 cP). A mixture of 100 parts of the abovesyrup, 0.2 parts IRGACURE 651, and any remaining components (epoxiesand/or alcohols) was made. The mixture was coated at 0.75 mm thicknessbetween two 0.050 mm silicone-coated poly(ethylene terephthalate)release liners. This construct was irradiated from each side with 1200mJ/cm² UVA from 350BL fluorescent bulbs, as measured by a UVIRAD® LowEnergy UV Integrating Radiometer (EIT, Inc., Sterling, Va.). Releaseliners were removed prior to subsequent compounding.

Preparatory Acrylic Mixtures P3-P7

Acrylic mixtures as shown in Table 5 below were prepared for use inExamples 10-21. The mixtures were prepared as generally taught in U.S.Pat. No. 5,804,610 (Hamer et al.). Solutions were prepared by combiningthe acrylic monomers, radical photoinitiator (IRGACURE 651) andchain-transfer agent (IOTG) in an amber glass jar and swirling by handto mix. The solution was divided into 25 g aliquots within heat sealedcompartments of an ethylene vinyl acetate-based film, immersed in a 16°C. water bath, and polymerized using UV light (UVA=4.7 mW cm⁻², 8minutes per side).

TABLE 5 (all numbers in wt %) Material P1 P2 P3 P4 P5 P6 P7 2-POEA 43IBOA 14 BA 35 49 49 50 70 75 THFa 23 49 49 50 23 MA 20 GMA 2 10 2 HBA 2EPON 828 29 31 EPON 1001F 10 8 Cyclohexane 2 4 dimethanol 1,6-hexanediol2 IRGACURE 651 0.24 0.24 0.2 0.2 0.2 0.2 0.2 IOTG 0.1 0.1 0.1 0.1 0.1

Examples 8-20

The acrylic mixtures P1-P7 were further processed to yield theepoxy-acrylic-based compositions listed in Table 6 below. Compositionswere prepared using a BRABENDER mixer (C. W. Brabender, Hackensack,N.J.) equipped with a 50 or 250 g capacity heated mix head and kneadingelements. The mixer was operated at the desired mixing temperature of120-150° C. and the kneading elements were operated at 100 rpm. Theacrylic copolymer was added and allowed to mix for several minutes. Thesolid epoxy

TABLE 6 (all numbers in wt %) Material Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Acrylic P1 P2 P3P3 P3 P3 P3 P3 P3 P4 P5 P6 P7 mixture 97 97 64 48 32 34 34 38 32 32 3232 32 (wt %) EPONEX — — 10 14 19 21 21 24 19 19 19 19 19 1510 EPON — —10 14 19 21 21 24 19 19 19 19 19 1001F ARCOL 240 — — 5 7 10 11 11 12 1010 10 10 10 LHT GPTMS — — 1 1 1 1 1 1 1 1 1 1 1 LEVAPREN — — 5 7 10 11 —— 10 10 10 10 10 700HV PHENOXY — — 5 7 10 — 11 — 10 10 10 10 10 PKHA UVI6976 2.9 2.8 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 PAG210S — — — — — —— — 0.5 — — — —resin and phenoxy resin were added and allowed to mix until uniformlydistributed through the mixture. The liquid epoxy resin and polyol werethen added slowly until uniformly distributed. The resulting mixture wasallowed to stir for several minutes and then the photoacid generator wasadded drop-wise. The mixture was allowed to stir several minutes and wasthen transferred to an aluminum pan and allowed to cool. The mixture wasthen placed between two release liners and was pressed, with heating to95° C., into 0.6 mm thick film by means of a hydraulic press (CarverInc., Wabash, Ind.).

The T_(g) of the acrylic polymer was measured prior to compounding. Testspecimens were prepared for evaluation of the overlap shear, cleavageand tensile pluck performance of the cured epoxy-acrylic-basedcompositions. Test specimens were cured by applying a portion of thecomposition to one substrate, irradiating with either a microwave or LEDsource, closing the bond, and allowing the specimen to cure asspecified. Cleavage and tensile pluck specimens were prepared usingCRASTIN test pieces and tempered glass. FTIR-ATR was used to determinethe extent of cure on both faces. The adhesive properties of the uncuredcompositions was determined by measuring the 90° peel adhesion and creepbehavior. Measured properties are shown in Table 7 below.

Examples 21-28

The parallel torque, vertical torque, and tensile pluck properties ofthe adhesive composition of Example 12, as related to UV exposure, wereevaluated and the results are shown in Table 8 below. Specimens wereprepared using GRIVORY test pieces and frit glass according to thegeneral test methods above. For Examples 21-24 only, the plastic testpiece was wiped with a lint-free tissue paper saturated with a primer,UVI-6976, applied after wiping the plastic test piece with isopropylalcohol/water but before applying the adhesive composition. Allspecimens were exposed to UVA from a 365 nm LED (7.5 J/cm², CLEARSTONETECHNOLOGIES, Hopkins, Minn.), were post-baked at 150° C. for 5 minutesand were then conditioned at ambient temperature and humidity for 24hours prior to mechanical testing.

TABLE 7 Test Method Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex.15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Overlap Shear (MPa) H-bulb, 24 h,0.3 1.0 2.6 5.0 6.5 8.9 11.5 10.0 6.2 6.9 8.5 0.4 1.5 RT 365 nm LED, 24h, — — — — 6.4 — — — — — — — — RT Cleavage (N) H-bulb, 24 h, 71 12 42128 161 123 45 125 156 126 151 20 48 RT 365 nm LED, 24 h, — — — — 139 —— — — — — — — RT FTIR-ATR H-bulb, C/C C/C — — C/C — — — C/C C/C C/C C/CC/C 70° C., 10 min H-bulb, 24 h, C/C C/C — — C/C — — — C/C C/C C/C C/CC/C RT 365 nm LED, 24 h, — — — — C/C — — — — — C/C — — RT 90 deg peel 1524 54 54 64 25 37 — — — 44 — — (N) Creep (% 55 623 118 162 167 474 4821250 — — 176 — — strain) Acrylic T_(g) — — −23 −23 −23 −23 −23 — −23 −24−24 −23 −33 (° C.) Appearance — — — — T — — — T T T O O H-bulb, 70° C.,10 min Tensile Pluck (N) H-bulb, 24 hr, — — — — — 1116 — — — — — 1271 —25° C. H-bulb, 24 hr, — — — — — 236 — — — — — 262 — 70° C.

TABLE 8 UVA Parallel Vertical Tensile energy torque torque Pluck Example(J/cm²) (N-m) (N-m) (N) 21 3 23 610 1179 22 7 22 678 237 23 13 29 700585 24 25 0 0 0 25 3 14 813 451 26 7 25 813 513 27 13 29 813 531 28 2525 813 1129

Examples 29-48

The parallel torque properties of the adhesive composition of Example12, as related to post-bake condition, were evaluated and results areshown in Table 9 below. Parallel torque specimens were preparedaccording to the general test methods above using the specified plastictest piece, glass substrate, and post-bake time and temperature listedin Table 9. Samples in Examples 29-34 were exposed to 7.5 J/cm² UVA froma 365 nm LED (CLEARSTONE TECHNOLOGIES, Hopkins, Minn.). Upon completionof the post-bake, samples were conditioned at ambient temperature andhumidity for 24 hours prior to testing. Parallel torque values arereported in Table 9 and are given in units of N-m.

Examples 49-53

FTIR-ATR was used to compare the curing properties of the adhesivecomposition of Example 12 upon exposure to radiation of differentprincipal wavelengths. LEDs with principle wavelengths of 365 nm or 395nm were used to initiate the curing reaction of the adhesivecomposition. A portion of the composition, with one liner removed, wasplaced in an aluminum pan and was exposed to the specified light sourcefor the specified

TABLE 9 Bake temper- ature Bake time Bake time Example Test Substrates(° C.) (10 min) (5 min) 29 CRASTIN/Frit glass 70 10 — 30 CRASTIN/Fritglass 90 12 — 31 CRASTIN/Frit glass 110 21 16 32 CRASTIN/Frit glass 130— 15 33 CRASTIN/Frit glass 150 — 17 34 CRASTIN/tempered glass 70  8 — 35CRASTIN/tempered glass 90  9 — 36 CRASTIN/tempered glass 110  7  8 37CRASTIN/tempered glass 130 —  7 38 CRASTIN/tempered glass 150 —  7 39GRIVORY/Frit glass 70 18 — 40 GRIVORY/Frit glass 90 40 — 41 GRIVORY/Fritglass 110 38 37 42 GRIVORY/Frit glass 130 — 30 43 GRIVORY/Frit glass 150— 33 44 GRIVORY/tempered glass 70 15 — 45 GRIVORY/tempered glass 90 13 —46 GRIVORY/tempered glass 110 11 13 47 GRIVORY/tempered glass 130 — 1148 GRIVORY/tempered glass 150 —  8duration. FTIR-ATR was then used to measure the cure upon exposure to UVradiation. Qualitative epoxy conversion data appear in Table 10. Theepoxy conversion was assessed according to the general Attenuated TotalReflectance method. Upon 4 seconds exposure to the 365 nm LED, thecomposition showed good conversion of epoxy as shown by thedisappearance of the 912 cm⁻¹ peak in the FTIR-ATR spectra. Yet, upon 24seconds exposure to the 395 nm LED, there is still presence of an epoxypeak at 912 cm⁻¹.

TABLE 10 Example LED used (nm) Exposure time (sec) Epoxy conversion 49365 1.2 P/P 50 365 4 P/C 51 365 8 C/C 52 395 0.8 U/U 53 395 24 U/U

Examples 54-57

The parallel torque and vertical torque properties of the adhesivecomposition of Example 12, as related to radiation source and totalexposure energy, were evaluated. Specimens were prepared using GRIVORYtest pieces and frit glass according to the general methods describedabove using the specified radiation source and exposure energy.Specimens were post-baked at 150° C. for 5 minutes and were thenconditioned at ambient temperature and humidity for 24 hours prior tomechanical testing. The parallel torque and vertical torque results areshown in Table 11 below.

TABLE 11 H Bulb 365 nm UVA LED UVA Parallel Vertical energy energytorque torque Example (J/cm²) (J/cm²) (N-m) (N-m) 54 0.8 — 16 576 55 1.4— 23 780 56 —  7 25 813 57 — 13 29 813

Examples 58-62

The parallel torque, vertical torque, tensile pluck, and cleavageproperties of the adhesive composition of Example 12, as related toexposure energy from a 365 nm LED, were evaluated. Specimens wereprepared using GRIVORY test pieces and frit glass according to thegeneral methods above using the specified exposure energy. The tensilepluck and cleavage samples were laminated to the plastic test specimenusing 138 kPa (20 psi) for 6 seconds and were laminated to the glasssubstrate upon activation using 207 kPa (30 psi) for 6 seconds. Allspecimens were post-baked at 150° C. for 5 minutes and were thenconditioned at ambient temperature and humidity for 24 hours prior tomechanical testing. Parallel torque, vertical torque, tensile pluck, andcleavage results are shown in Table 12 below. It is noted that Examples59-62 are the same as Examples 25-28 in Table 8, and are merely includedin this table for comparison purposes.

TABLE 12 UV Parallel Vertical Tensile dosage torque torque pluckCleavage Example (J/cm²) (N-m) (N-m) (N) (N) 58 1 11 705 246 89 59 3 14813 451 187 60 7 25 813 513 144 61 13 29 813 531 116 62 25 25 813 1129142

Examples 63-65

The overlap shear properties of the adhesive composition of Example 12,as related to film thickness and radiation source, were evaluated.Overlap shear specimens of the specified film thickness were preparedaccording to the general methods above using the specified radiationsource. All samples were laminated at a pressure of 207 kPa (30 psi) for6 seconds. An exposure energy of 1.4 J/cm² was measured for specimensirradiated with the H-Bulb source. An exposure energy of 7.6 J/cm² wasmeasured for specimens irradiated with the 365 nm LED source. An EIT UVPower Puck II designated to measure UVA radiation in the range of315-400 nm was used to measure the exposure energy. Specimens wereallowed to cure at ambient temperature and humidity for 24 hours priorto mechanical testing. The overlap shear test results are reported inTable 13 below.

TABLE 13 Thickness Overlap shear strength Overlap shear strength Example(microns) (H bulb, MPa) (365 nm LED, MPa) 63 635 17.2 16.7 64 1270 4.412.8 65 1905 1.2 13.5

Examples 66-68

The bond strength of the adhesive composition of Example 12 on laminatedvehicular glass was evaluated according the Windshield Adhesion Test.Results appear in Table 14 below.

TABLE 14 Example Curing Time Bond strength (MPa) 66 10 min 0.3 67  2hours 6.1 68 24 hours 8.2

All cited references, patents, and patent applications in the aboveapplication for letters patent are herein incorporated by reference intheir entirety in a consistent manner. In the event of inconsistenciesor contradictions between portions of the incorporated references andthis application, the information in the preceding description shallcontrol. The preceding description, given in order to enable one ofordinary skill in the art to practice the claimed disclosure, is not tobe construed as limiting the scope of the disclosure, which is definedby the claims and all equivalents thereto.

1. A method of bonding hardware to glass comprising: providing thehardware and the glass; disposing an adhesive layer on a bonding surfaceof either the hardware or the glass, the adhesive layer comprising anultraviolet radiation curable composition that is dimensionally stableat ambient conditions; either before or after disposing the adhesivelayer on the bonding surface, irradiating the adhesive layer withultraviolet radiation to cause curing of the curable composition;placing the hardware so as to be bonded to the glass by the adhesivelayer; and allowing the adhesive layer to cure.
 2. The method of claim1, wherein the curable composition comprises: a) in the range of fromabout 25 to about 80 parts by weight of one or more epoxy resins; b) inthe range of from about 5 to about 30 parts by weight of one or moreliquid polyether polyols; c) in the range of from about 10 to about 50parts by weight of one or more hydroxyl-functional film-forming polymersor precursors thereof, wherein the sum of a) to c) is 100 parts byweight; and d) in the range of from about 0.1 to about 5 parts by weightof a photoinitiator, relative to the 100 parts of a) to c).
 3. Themethod of claim 1, wherein the photoinitiator has an ultravioletabsorption curve characterized by a highest wavelength absorption peakmeasured at a concentration of about 0.03 wt % in acetonitrile solutionand wherein the ultraviolet radiation has a spectral power distributionpositively offset from the wavelength of the highest wavelengthabsorption peak.
 4. The method of claim 1, wherein the highestwavelength absorption peak is located at a wavelength of at most about395 nm.
 5. A method of bonding hardware to glass comprising: disposingan adhesive layer on a bonding surface of either the hardware or theglass, the adhesive layer comprising an ultraviolet radiation curablecomposition comprised of: a) in the range of from about 25 to about 80parts by weight of one or more epoxy resins; b) in the range of fromabout 5 to about 30 parts by weight of one or more liquid polyetherpolyols; c) in the range of from about 10 to about 50 parts by weight ofone or more hydroxyl-functional film-forming polymers and precursorsthereof, wherein the sum of a) to c) is 100 parts per weight; and d) inthe range of from about 0.1 to about 5 parts by weight of aphotoinitiator, relative to the 100 parts of a) to c); either before orafter disposing the adhesive layer on the bonding surface, irradiatingthe adhesive layer with ultraviolet radiation to cause curing of thecurable composition; placing the hardware so as to be bonded to theglass by the adhesive layer; and allowing the adhesive layer to cure. 6.A method of bonding hardware to glass comprising: disposing an adhesivelayer on a bonding surface of either the hardware or the glass, theadhesive layer comprising an ultraviolet radiation curable compositioncomprised of: a) in the range of from about 1 to about 50 parts byweight of one or more resins selected from (meth)acrylate resins; b) inthe range of from about 12 to about 40 parts by weight of one or morehydroxyl-functional film-forming polymers and precursors thereof; c) inthe range of from about 20 to about 75 parts by weight of one or moreepoxy resins; d) in the range of from about 10 to about 30 parts byweight of one or more polyether polyols, wherein the sum of a) to d) is100 parts by weight; and e) in the range of from about 0.1 to about 5parts by weight of a photoinitiator, relative to the 100 parts of a) tod); either before or after disposing the adhesive layer on the bondingsurface, irradiating the adhesive layer with ultraviolet radiation tocause curing of the curable composition; placing the hardware so as tobe bonded to the glass by the adhesive layer; and allowing the adhesivelayer to cure.
 7. The method of claim 6, wherein the curable compositioncomprises: i) in the range of from about 15 to about 50 parts by weightof a tetrahydrofurfuryl (meth)acrylate copolymer; ii) in the range offrom about 25 to about 50 parts by weight of the one or more epoxyresins; iii) in the range of from about 5 to about 15 parts by weight ofthe one or more liquid polyether polyols; iv) in the range of from about10 to about 25 parts by weight of one or more hydroxyl-functionalfilm-forming polymers and precursors thereof, wherein the sum of i) toiv) is 100 parts by weight; and v) in the range of from about 0.1 toabout 5 parts by weight of a cationic photoinitiator, relative to the100 parts of i) to iv).
 8. The method of claim 7, wherein thetetrahydrofurfuryl (meth)acrylate copolymer comprises: A) in the rangeof from about 40 to about 60 wt % of tetrahydrofurfuryl (meth)acrylate;B) in the range of from about 40 to about 60 wt % of C₁-C₈ alkyl(meth)acrylate ester; and C) in the range of from 0 to about 10 wt % ofcationically reactive functional monomer, wherein the sum of A)-C) is100 wt %.
 9. The method of claim 5, wherein the photoinitiator has anultraviolet absorption curve characterized by a highest wavelengthabsorption peak measured at a concentration of about 0.03 wt % inacetonitrile solution and wherein the ultraviolet radiation has aspectral power distribution positively offset from the wavelength of thehighest wavelength absorption peak.
 10. A method of bonding hardware toglass comprising: disposing an adhesive layer on a bonding surface ofeither the hardware or the glass, the adhesive layer comprising anultraviolet radiation curable composition comprised of: a) in the rangeof from about 15 to about 50 parts by weight of a semi-crystallinepolyester resin; b) in the range of from about 20 to about 75 parts byweight of one or more epoxy resins; c) in the range of from about 5 toabout 15 parts by weight of one or more liquid polyether polyols; d) inthe range of from about 5 to about 20 parts by weight of one or morehydroxyl-functional film-forming polymers and precursors thereof,wherein the sum of a) to d) is 100 parts by weight; and e) in the rangeof from about 0.1 to about 5 parts by weight of a photoinitiator,relative to the 100 parts of a) to d); either before or after disposingthe adhesive layer on the bonding surface, irradiating the adhesivelayer with ultraviolet radiation to cause curing of the curablecomposition, wherein the photoinitiator has an ultraviolet absorptioncurve characterized by a highest wavelength absorption peak measured ata concentration of about 0.03 wt % in acetonitrile solution and whereinthe ultraviolet radiation has a spectral power distribution positivelyoffset from the wavelength of the highest wavelength absorption peak;placing the hardware so as to be bonded to the glass by the adhesivelayer; and allowing the adhesive layer to cure.
 11. The method of claim1, wherein the one or more hydroxy-functional film forming polymers areselected from phenoxy resins, ethylene-vinyl acetate copolymers,polycaprolactone polyols, polyester polyols, and polyvinyl acetalresins.
 12. A method of bonding hardware to glass comprising: disposingan adhesive layer on a bonding surface of either the hardware or theglass, the adhesive layer comprising an ultraviolet radiation curablecomposition having an ultraviolet absorption curve characterized by ahighest wavelength absorption peak measured at a concentration of about0.03 wt % in acetonitrile solution; either before or after disposing theadhesive layer on the bonding surface, irradiating the adhesive layerwith ultraviolet radiation to cause curing of the curable composition,wherein the ultraviolet radiation has a spectral power distributionpositively offset from the wavelength of the highest wavelengthabsorption peak; placing the hardware so as to be bonded to the glass bythe adhesive layer; and allowing the adhesive layer to cure.
 13. Themethod of claim 12, wherein the spectral power distribution has a peakintensity at a wavelength in the range of from about 315 nm to about 400nm.
 14. The method of claim 12, wherein the spectral power distributionsubstantially excludes wavelengths below about 280 nm.
 15. The method ofclaim 12, wherein the highest wavelength absorption peak is located at awavelength of at most about 395 nm.
 16. The method of claim 1, whereinthe glass is vehicular and/or architectural glass comprising a firstsheet of glass, a polymeric backing, and a second sheet of glass,laminated in that order via an autoclaving process.
 17. The method ofclaim 5, wherein the glass is vehicular and/or architectural glass. 18.The method of claim 6, wherein the glass is vehicular and/orarchitectural glass.
 19. The method of claim 10, wherein the glass isvehicular and/or architectural glass.
 20. The method of claim 12,wherein the glass is vehicular and/or architectural glass.